Q20Long answer
If sin (θ + α) = a and sin (θ + β) = b, then prove that cos 2(α – β) – 4ab cos (α – β) = 1 – 2a2 – 2b2 [Hint: Express cos (α – β) = cos ((θ + α) – (θ + β))] 1− m
If sin (θ + α) = a and sin (θ + β) = b, then prove that cos 2(α – β) – 4ab cos (α – β) = 1 – 2a2 – 2b2 [Hint: Express cos (α – β) = cos ((θ + α) – (θ + β))] 1− m