This video lecture from Trigonometric Identities (F.Sc. first year Mathematics) covers: Question numbers 9-10 of exercise 10.2. In these questions we are given with the values of sin(alpha) and sine(beta), and quadrant of these angles. using this information we find the values of other trigonometric functions and then prove the given trigonometric equation. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.