cos^2x-sin^2x +2sinxcosx
=cos2x+sin2x
=√2(cos2xsinΠ/4+sin2xcosΠ/4)
=√2sin(2x+Π/4)
谁能解答一下cos平方x—sin平方x等于什么?还有2sinxcosx等于什么?还有给我一下第二步到第三步的详细过程,
cos^2x-sin^2x +2sinxcosx
=cos2x+sin2x
=√2(cos2xsinΠ/4+sin2xcosΠ/4)
=√2sin(2x+Π/4)