Question

помогите решить ctgasin2a-cos2a

Answer 1

$Ctg alpha Sin2 alpha -Cos2 alpha = frac{Cos alpha }{Sin alpha }*2Sin alpha Cos alpha -Cos2 alpha=2Cos ^{2} alpha -$$(2Cos ^{2} alpha -1)=2Cos ^{2} alpha -2Cos ^{2} alpha +1=1$

Answer 2

$ctg asin 2a-cos 2a=frac{sin 2acdot cos a-cos 2acdot sin a}{sin a}= frac{sin(2a-a)}{sin a}=frac{sin a}{sin a}=1$