已知sin^2X+sinX=1,求cos^4X=cos^2X的值

问题描述:

已知sin^2X+sinX=1,求cos^4X=cos^2X的值

sin^2X+sinX=1,sinX=1-sin^2X=cos^2X cos^4X=sin^2X
cos^4X=cos^2X中间应该是+?
cos^4+cos^2X=sin^2X+cos^2X=1