同角三角函数化简 急cos^4 + sin^2cos^2 + sin^2 + tan^2

问题描述:

同角三角函数化简 急
cos^4 + sin^2cos^2 + sin^2 + tan^2

由于sin^2=1-cos^2
代入得:cos^4+(1-cos^2)cos^2+(1-cos^2)+(1-cos^2)/cos^2
=1/cos^2