Question

(sina+cosa)2 -2sinacosa​

Answer 1

$(a+b)^2-2ab=a^2+b^2\\\\(sina+cosa)^2 -2sinacosa=sin^2a+cos^2a=1$

Answer 2

(sina+cosa)² -2sinacosa​=sin²a+2sinacosa+cos²a-2sinacosa=sin²a+cos²a=1

Ответ: 1