This video lecture from Trigonometric Identities (F.Sc. first year Mathematics) covers: Question number 8 of exercise 10.2. In this question we are given with the values of sin(alpha) and cos(beta), using this information we 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.