Question

Derive the formula of sin2A and cos2A.

Answer 1

Step-by-step explanation:

sin2A = 2sinAcosA.

Both sin (2A) and cos (2A) are derived from the double angle formula for the cosine: cos (2A) = cos2(A) − sin2(A) = cos2(A) − (1 − cos2A) = 2cos2(A) − 1. So, . If we now replace A by (1/2)A, and take the square root we get: .