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        <title>MathCity.org</title>
        <description>Merging man &amp; maths</description>
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        <item>
            <title>Question 1, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p1</link>
            <description>Question 1, Exercise 10.1

Solutions of Question 1 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan. There are four parts in Question 1.$\sin {{37}^{\circ }}\cos {{22}^{\circ }}+\cos {{37}^{\circ }}\sin {{22}^{\circ }}$\begin{align} \sin (\alpha +\beta )=\sin \alpha \cos \beta +\cos \alpha \sin \beta, \end{align}\begin{a…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:35 +0000</pubDate>
        </item>
        <item>
            <title>Definitions: FSc Part1 KPK</title>
            <link>https://www.mathcity.org/math-11-kpk/definitions</link>
            <description>Definitions: FSc Part1 KPK

A Textbook of Mathematics for Class XI is published by Khybar Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan. The book has total of twelve (12) chapters.

Definition of the book provide the quick overview of the book.$360^\circ$$\theta$$90^{\circ} \pm \theta, 180^{\circ} \pm \theta, 270^{\circ} \pm \theta, 360^{\circ} \pm \theta$$16^\circ 13&#039; 9&#039;&#039;$$sin(\alpha+2\pi)=sin\alpha$$sin x=\frac{2}{7}$$cos x-tan x=0$</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:44:42 +0000</pubDate>
        </item>
        <item>
            <title>Unit 10: Trigonometric Identities of Sum and Difference of Angles (Solutions)</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10</link>
            <description>Unit 10: Trigonometric Identities of Sum and Difference of Angles (Solutions)

This is a tenth unit of the book Mathematics 11 published by Khyber Pakhtunkhwa Textbook Board, Peshawar, Pakistan. On this page we have provided the solutions of the questions.$a\sin\theta + b\cos \theta$$r\sin(\theta +\psi )$$a = r\cos\psi$$b=r\sin\psi$</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:44:48 +0000</pubDate>
        </item>
        <item>
            <title>Question 2, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p2</link>
            <description>Question 2, Exercise 10.1

Solutions of Question 2 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\sin \dfrac{\pi }{12}$$\dfrac{\pi }{12}$$\dfrac{\pi }{3}-\dfrac{\pi }{4}$\begin{align}\sin (\alpha -\beta )=\sin \alpha \cos \beta -\cos \alpha \sin.\end{align}\begin{align} \Rightarrow \quad \sin \left( \frac{\pi }{3}-\f…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:37 +0000</pubDate>
        </item>
        <item>
            <title>Question 3, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p3</link>
            <description>Question 3, Exercise 10.1

Solutions of Question 3 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\sin u=\dfrac{3}{5}$$\sin v=\dfrac{4}{5}$$u$$v$$0$$\dfrac{\pi }{2}$$\cos \left( u+v \right)$$\sin u=\dfrac{3}{5},$$0\le u\le \dfrac{\pi }{2}.$$\sin v=\dfrac{4}{5},$$0\le v\le \dfrac{\pi }{2}.$$\cos u=\pm \sqrt{1-{{\sin }^…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:40 +0000</pubDate>
        </item>
        <item>
            <title>Question, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p4</link>
            <description>Question, Exercise 10.1

Solutions of Question 4 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\sin \alpha =-\dfrac{4}{5}$$\cos \beta =-\dfrac{12}{13}$$\alpha $$\beta $$\sin \left( \alpha -\beta  \right)$$\sin \alpha=-\dfrac{4}{5}$$\alpha$$\sin \beta=-\dfrac{12}{13}$$\beta$$$\cos \alpha=\pm \sqrt{1-\sin^2\alpha}.$$$\…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:39 +0000</pubDate>
        </item>
        <item>
            <title>Question 5, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p5</link>
            <description>Question 5, Exercise 10.1

Solutions of Question 5 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\tan \alpha =\dfrac{3}{4}$$\sec \beta =\dfrac{13}{5}$$\alpha$$\beta$$\sin \left( \alpha +\beta  \right)$$\tan\alpha =\dfrac{3}{4}$$\tan\alpha$$\alpha$\begin{align}{{\sec}^{2}}\alpha &amp;=1+{{\tan}^{2}}\alpha\\
\Rightarrow \q…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:42 +0000</pubDate>
        </item>
        <item>
            <title>Question 6, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p6</link>
            <description>Question 6, Exercise 10.1

Solutions of Question 1 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\cos \alpha =2{{\cos }^{2}}\dfrac{\alpha }{2}-1=1-2{{\sin }^{2}}\dfrac{\alpha }{2}$\begin{align}\cos \alpha &amp;=\cos 2\dfrac{\alpha }{2}\\
&amp;={{\cos }^{2}}\dfrac{\alpha }{2}-{{\sin }^{2}}\dfrac{\alpha }{2}\\ 
&amp;={{\cos }^{2}}…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:42 +0000</pubDate>
        </item>
        <item>
            <title>Question 7, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p7</link>
            <description>Question 7, Exercise 10.1

Solutions of Question 1 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\cot \left( \alpha +\beta  \right)=\dfrac{\cot \alpha \cot \beta -1}{\cot \alpha +\cot \beta }$\begin{align}L.H.S.&amp;=\cot (\alpha +\beta )\\
&amp;=\dfrac{1}{\tan (\alpha +\beta )}\\
&amp;=\dfrac{1}{\,\dfrac{\tan \alpha +\tan \beta…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:44 +0000</pubDate>
        </item>
        <item>
            <title>Question 8, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p8</link>
            <description>Question 8, Exercise 10.1

Solutions of Question 8 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\tan \left( \dfrac{\pi }{4}+\theta  \right)=\dfrac{\cos \theta +\sin \theta }{\cos \theta -\sin \theta }$\begin{align}L.H.S.&amp;=\tan \left( \dfrac{\pi }{4}+\theta  \right)\\ 
&amp;=\dfrac{\sin \left( \dfrac{\pi }{4}+\theta  \ri…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:44 +0000</pubDate>
        </item>
        <item>
            <title>Question 9 and 10, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p9</link>
            <description>Question 9 and 10, Exercise 10.1

Solutions of Question 9 and 10 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\dfrac{\sin \theta }{\sec 4\theta }+\dfrac{\cos \theta }{\cos ec4\theta }=\sin 5\theta $\begin{align}L.H.S.&amp;=\dfrac{\sin \theta }{\sec 4\theta }+\dfrac{\cos \theta }{\cos ec4\theta }\\
&amp;=\dfrac{\sin \theta }…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:47 +0000</pubDate>
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        <item>
            <title>Question11 and 12, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p10</link>
            <description>Question11 and 12, Exercise 10.1

Solutions of Question 11 and 12 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\alpha$$\beta$$\gamma$$ABC$$\cot \dfrac{\alpha }{2}+\cot \dfrac{\beta }{2}+\cot \dfrac{\gamma }{2}=\cot \dfrac{\alpha }{2}\cot \dfrac{\beta }{2}\cot \dfrac{\gamma }{2}$$\alpha$$\beta$$\gamma$\begin{align}&amp;\…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:35 +0000</pubDate>
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        <item>
            <title>Question 13, Exercise 10.1</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-1-p11</link>
            <description>Question 13, Exercise 10.1

Solutions of Question 13 of Exercise 10.1 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$r\,\,\sin \left( \theta +\phi  \right)$$\theta$$\phi$$4\sin \theta +3\cos \theta .$$4\sin \theta +3\cos \theta$$r\sin(\theta + \varphi)$$$4\sin \theta +3\cos \theta=r\cos\varphi\sin\theta+r\sin\varphi\cos\theta --- (1)$…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:37 +0000</pubDate>
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        <item>
            <title>Question 1, Exercise 10.2</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-2-p1</link>
            <description>Question 1, Exercise 10.2

Solutions of Question 1 of Exercise 10.2 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan. There are four parts in Question 1.$\sin 2\theta ,\,\,\cos 2\theta$$\tan 2\theta$$\tan \theta =-\dfrac{1}{5}$$\theta$$\sin \theta =\dfrac{1}{\sqrt{26}}$$\cos \theta =\dfrac{-5}{\sqrt{26}}$\begin{align}\sin 2\theta &amp;=2\sin…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:47 +0000</pubDate>
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        <item>
            <title>Question 2, Exercise 10.2</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-2-p2</link>
            <description>Question 2, Exercise 10.2

Solutions of Question 2 of Exercise 10.2 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\sin \theta =\dfrac{5}{13}$$\theta $$\sin 2\theta $$\sin \theta =\dfrac{5}{13}$$$\cos \theta =\pm \sqrt{1-{{\sin }^{2}}\theta }.$$$\theta$$\cos$\begin{align}\cos\theta &amp;=-\sqrt{1-{{\sin }^{2}}\theta }\\
&amp;=-\sqrt{1-\left(\…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:52 +0000</pubDate>
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        <item>
            <title>Question 3, Exercise 10.2</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-2-p3</link>
            <description>Question 3, Exercise 10.2

Solutions of Question 3 of Exercise 10.2 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\sin \theta =\dfrac{4}{5}$$\theta$$\sin2\theta$$\sin \theta =\dfrac{4}{5}$$\theta$$\cos \theta =-\dfrac{3}{5}$\begin{align}\sin 2\theta &amp;=2\sin \theta \cos \theta \\
&amp;=2\left( \dfrac{4}{5} \right)\left( -\dfrac{3}{5} \rig…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:52 +0000</pubDate>
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        <item>
            <title>Question 4 and 5, Exercise 10.2</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-2-p4</link>
            <description>Question 4 and 5, Exercise 10.2

Solutions of Question 4 and 5 of Exercise 10.2 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\cos \theta =-\dfrac{3}{7}$$\theta $$\sin \dfrac{\theta }{2}$$\cos \theta =-\dfrac{3}{7}$$\theta$\begin{align}&amp;\pi &lt; \theta &lt; \dfrac{3\pi}{2} \\
\implies &amp;\frac{\pi}{2} &lt; \frac{\theta}{2} &lt; \dfrac{3\pi}{4}\end…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:55 +0000</pubDate>
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        <item>
            <title>Question 6, Exercise 10.2</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-2-p5</link>
            <description>Question 6, Exercise 10.2

Solutions of Question 6 of Exercise 10.2 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\cos {{15}^{\circ }}$${{15}^{\circ }}=\dfrac{{{30}^{\circ }}}{2}$$\dfrac{\theta }{2}=\dfrac{{{30}^{\circ }}}{2}$$\cos {{15}^{\circ }}$\begin{align}\cos {{15}^{\circ }}&amp;=\cos \dfrac{{{30}^{\circ }}}{2}=\sqrt{\dfrac{1+\cos …</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:45:55 +0000</pubDate>
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        <item>
            <title>Question 7, Exercise 10.2</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-2-p6</link>
            <description>Question 7, Exercise 10.2

Solutions of Question 7 of Exercise 10.2 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.${{\cos }^{4}}\theta -{{\sin }^{4}}\theta =\dfrac{1}{\sec 2\theta }$\begin{align}L.H.S&amp;={{\cos }^{4}}\theta -{{\sin }^{4}}\theta \\ 
&amp;=\left( {{\cos }^{2}}\theta -{{\sin }^{2}}\theta  \right)\left( {{\cos }^{2}}\theta +{{\…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:00 +0000</pubDate>
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        <item>
            <title>Question 8 and 9, Exercise 10.2</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-2-p7</link>
            <description>Question 8 and 9, Exercise 10.2

Solutions of Question 8 and 9 of Exercise 10.2 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.${{\cos }^{4}}\theta $\begin{align}{{\cos}^{4}}\theta &amp;={{\left( {{\cos }^{2}}\theta  \right)}^{2}}\\
&amp;={{\left( \dfrac{1+\cos 2\theta }{2} \right)}^{2}}\\ 
&amp;=\dfrac{1+2\cos 2\theta +{{\cos }^{2}}2\theta }{4}\\…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:00 +0000</pubDate>
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        <item>
            <title>Question 1, Exercise 10.3</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-3-p1</link>
            <description>Question 1, Exercise 10.3

Solutions of Question 1 of Exercise 10.3 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan. There are four parts in Question 1.$2\sin 6x\sin x$$$-2\sin \alpha \sin \beta =\cos (\alpha +\beta )-\cos (\alpha -\beta ).$$$\alpha =6x$$\beta =x$\begin{align}-\,2\sin 6x\sin x&amp;=\cos (6x+x)-\cos (6x-x)\\
&amp;=\cos 7x-\cos x…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:02 +0000</pubDate>
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        <item>
            <title>Question 2, Exercise 10.3</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-3-p2</link>
            <description>Question 2, Exercise 10.3

Solutions of Question 2 of Exercise 10.3 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$$\sin {{37}^{\circ }}+\sin {{43}^{\circ }}.$$$$\sin \alpha +\sin \beta =2\sin \left( \dfrac{\alpha +\beta }{2} \right)\cos \left( \dfrac{\alpha -\beta }{2} \right).$$$\alpha ={{37}^{\circ }}$$\beta ={{43}^{\circ }}$\begin…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:02 +0000</pubDate>
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        <item>
            <title>Question 3, Exercise 10.3</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-3-p3</link>
            <description>Question 3, Exercise 10.3

Solutions of Question 3 of Exercise 10.3 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$$\dfrac{\cos {{75}^{\circ }}+\cos {{15}^{\circ }}}{\sin {{75}^{\circ }}-\sin {{15}^{\circ }}}=\sqrt{3}.$$$$\cos \alpha +\cos \beta =2\cos \left( \dfrac{\alpha +\beta }{2} \right)\cos \left( \dfrac{\alpha -\beta }{2} \righ…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:04 +0000</pubDate>
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        <item>
            <title>Question 5, Exercise 10.3</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-3-p4</link>
            <description>Question 5, Exercise 10.3

Solutions of Question 5 of Exercise 10.3 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$$\cos {{20}^{\circ }}\cos {{40}^{\circ }}\cos {{60}^{\circ }}\cos {{80}^{\circ }}=\dfrac{1}{16}.$$$2\cos \alpha \cos \beta =\cos \left( \alpha +\beta  \right)+\cos \left( \alpha -\beta  \right)$\begin{align}L.H.S.&amp;=\cos {…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:05 +0000</pubDate>
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        <item>
            <title>Question 5, Exercise 10.3</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/ex10-3-p5</link>
            <description>Question 5, Exercise 10.3

Solutions of Question 5 of Exercise 10.3 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\cos {{20}^{\circ }}\cos {{40}^{\circ }}\cos {{60}^{\circ }}\cos {{80}^{\circ }}=\dfrac{1}{16}$$2\cos \alpha \cos \beta =\cos \left( \alpha +\beta  \right)+\cos \left( \alpha -\beta  \right)$\begin{align}L.H.S.&amp;=\cos {{20…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:06 +0000</pubDate>
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        <item>
            <title>Question 1, Review Exercise 10</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/re-ex10-p1</link>
            <description>Question 1, Review Exercise 10

Solutions of Question 1 of Review Exercise 10 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\cos {{50}^{\circ }}5{0}&#039;\cos {{9}^{\circ }}1{0}&#039;-\sin {{50}^{\circ }}5{0}&#039;\sin {{9}^{\circ }}1{0}&#039;=$$0$$\dfrac{1}{2}$$1$$\dfrac{\sqrt{3}}{2}$$\dfrac{1}{2}$$\tan {{15}^{\circ }}=2-\sqrt{3}$${{\cot }^{2}}{{75}^{\…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Sat, 16 Mar 2024 13:12:33 +0000</pubDate>
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        <item>
            <title>Question 2 and 3, Review Exercise 10</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/re-ex10-p2</link>
            <description>Question 2 and 3, Review Exercise 10

Solutions of Question 2 and 3 of Review Exercise 10 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\dfrac{2\sin \theta \sin 2\theta }{\cos \theta +\cos 3\theta }=\tan 2\theta \tan \theta $\begin{align}L.H.S.&amp;=\dfrac{2\sin \theta \sin 2\theta }{\cos \theta +\cos 3\theta }\\
&amp;=\dfrac{2\sin \theta \s…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:19 +0000</pubDate>
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        <item>
            <title>Question 4 &amp; 5, Review Exercise 10</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/re-ex10-p3</link>
            <description>Question 4 &amp; 5, Review Exercise 10

Solutions of Question 4 &amp; 5 of Review Exercise 10 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.${{\sin }^{2}}\dfrac{\theta }{2}=\dfrac{\sin \theta \tan \dfrac{\theta }{2}}{2}$\begin{align}R.H.S.&amp;=\dfrac{\sin \theta \tan \dfrac{\theta }{2}}{2}\\
&amp;=\dfrac{\sin \theta \sin \dfrac{\theta }{2}}{2\cos \d…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:19 +0000</pubDate>
        </item>
        <item>
            <title>Question 6 &amp; 7, Review Exercise 10</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/re-ex10-p4</link>
            <description>Question 6 &amp; 7, Review Exercise 10

Solutions of Question 6 &amp; 7 of Review Exercise 10 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\cos 4\theta =1-8{{\sin }^{2}}\theta {{\cos }^{2}}\theta $\begin{align}L.H.S&amp;=\cos 4\theta \\
&amp;=\cos 2\left( 2\theta  \right)\\
&amp;=1-2\sin^2 2\theta \\
&amp;=1-2{{\left( 2\sin\theta \cos \theta  \right)}^{2}}…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:28 +0000</pubDate>
        </item>
        <item>
            <title>Question 8 &amp; 9, Review Exercise 10</title>
            <link>https://www.mathcity.org/math-11-kpk/sol/unit10/re-ex10-p5</link>
            <description>Question 8 &amp; 9, Review Exercise 10

Solutions of Question 8 &amp; 9 of Review Exercise 10 of Unit 10: Trigonometric Identities of Sum and Difference of Angles. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.$\sin \left( \dfrac{\pi }{4}-\theta  \right)\sin \left( \dfrac{\pi }{4}+\theta  \right)=\dfrac{1}{2}\cos 2\theta $$2\sin \alpha \sin \beta =\cos \left( \alpha -\beta  \right)-\cos \left( \alpha +\beta  \r…</description>
            <author>anonymous@undisclosed.example.com (Anonymous)</author>
            <pubDate>Tue, 05 Dec 2023 02:46:32 +0000</pubDate>
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