This video lecture from Trigonometric Identities (F.Sc. first year Mathematics) covers: Question numbers 1-3 of exercise 10.3. In these questions we are given with the value of sine(alpha) and we find the values of double angle trigonometric functions and prove the given trigonometric equations. 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.