Question

Упростить
cos (60+a)*cos(60-a)+sin^2a
a - это альфа
СРОЧНО

Answer 1

cos (60+α)*cos(60-α)+sin^2α=(cos60°cosα-sin60°sinα)*(cos60°cosα+sin60°sinα)+sin²α=(cos²60°cos²α-sin²60°sin²α)+sin²α=

(1/4)cos²α-(3/4)sin²α+sin²α=(1/4)(cos²α+sin²α)=(1/4)*1=0.25