Question

Ықшамданыз; sin²a + cos² a -1

Answer 1

(sin²a + cos² a )  - 1  = 1 - 1 = 0 

Answer 2

$sin ^{2} a+cos ^{2} a-1=0 \\ \\ 1)sin ^{2} a+cos ^{2} a=1 \\ 2)1-1=0$