Question

化简（2sinα+cosα）²+（2cosα-sinα）²

Answer 1

4sina²+4sinacosa+cosa²+4cosa²-4cosasina+sina²
=4(sina²+cosa²)+sina²+cosa²
=4+1
=5

Answer 2

（2sinα+cosα）²+（2cosα-sinα）² =4(sin^2a+cos^2a)+sin^2a+cos^2a=5