Question

Verify the formula (cos(α-β) = cos α cos β + sin α sin β) for each of the following values of α and β:
a) α = $\frac{2\pi }{3}$ , β = $\frac{\pi }{3}$
b) α = $\frac{3\pi }{4}$ , β = $\frac{\pi }{4}$

Answer 1

answer is 9/16×2=9/32