Question

Considerando sen(x) = 1/2 . (sen(25π/6)), o valor do cos(2x) será:

Answer 1

Considerando sen(x) = 1/2 . (sen(25π/6)), o valor do cos(2x) será:

sen(25π/6) = 1/2

sen(x) = 1/2 * 1/2 = 1/4

agora

cos(2x) = 1 - 2sen²(x)

cos(2x) = 1 - 2*1/16 = 1 - 1/8 = 7/8