2cos2x+sin^2x 化简

2cos2x+sin^2x 化简

2cos2x+sin^2x
=2(cos^2x-sin^2x)+sin^2x
=2cos^2x-sin^2x
=3cos^2x-1

2cos2x+sin^2x=2(2cos^2x-1)+sin^2x=4cos^2x-2+sin^2x=3cos^2x+cos^2x+sin^2x-2=3cos^2x+1-2=3cos^2x-1