Question

2cos2x+sin^2x,если sin x=1/3 . Найти значение выражения

Answer 1

2cos 2x + sin^2 x = 2(1 - 2 sin^2x) + sin^2 x =2 - 4 sin^2 x + sin^2 x =
=2 - 3 sin^2 x = 2 - 3 * (1/3)^2 = 2 - 3 * 1/9 = 2 - 1/3 = 5/3