Question

同位三角函数的求证（1）证明：sin^4x+cos^4x=1-2sin^2x*cos^2x请写出证明过程,

Answer 1

左边－右边=sin^4x+cos^4x-1+2sin^2xcos^2x

=(sin^2x+cos^2x)^2-1

=1-1

=0