Question

(sin a-cosa)^2 + sin 2a

Answer 1

sin2a=2sinacosa,  sin²a+cos²a=1 , (a-b)²=a²-2ab+b²  ⇒

(sina-cosa)²+sin2a=sin²a-2sina*cosa+cos²a+sin2a
=sin²a+cos²a -2sin2a+sin2a=1-sin2a