Question

函数y=2cos^2(x-π|4)-1的奇偶性

Answer 1

y=2cos²(x-π/4) -1

=cos[2(x-π/4)]+1-1

=cos(2x-π/2)

=cos(π/2 -2x)

=sin(2x)

sin(-2x)=-sin(2x)

函数是奇函数.