Question

for the function f(x) = sin x, show with the aid of the elementary formula sin^2 A = (1/2)(1 - cos2A) that f(x + y) - f(x) = cos x sin y - 2sin x sin^2(1/2 y)

Answer 1

f(x) = sin x

f(x+y)=............

Answer 2

uhm.... I don't get it