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.
Chose the correct option.
i. $\cos {{50}^{\circ }}5{0}'\cos {{9}^{\circ }}1{0}'-\sin {{50}^{\circ }}5{0}'\sin {{9}^{\circ }}1{0}'=$
ii. If $\tan {{15}^{\circ }}=2-\sqrt{3}$, then the value of ${{\cot }^{2}}{{75}^{\circ }}$ is
iii. If $\tan \left( \alpha +\beta \right)=\dfrac{1}{2}$, and $\tan \alpha =\dfrac{1}{3}$ then $\tan \beta =$
iv. $\sin \theta \cos \left( {{90}^{\circ }}-\theta \right)+\cos \theta \sin \left( {{90}^{\circ }}-\theta \right)=$
v. Simplified expression of $\left( \sec \theta +\tan \theta \right)\left( 1-\sin \theta \right)$ is
vi. $\sin \left( x-\frac{\pi }{2} \right)=$ is
vii. A point is in Quadrant-III and on the unit circle. If its x-coordinate is $-\dfrac{4}{5},$ what is the y-coordinate of the point?
viii. Which of the following is an identity?