因为sina+sina^2=1 所以sina=1-sina^2
3cosa^2+cosa^4-2sina+1
=3(1-sina^2)+(1-sina^2)^2-2sina+1
=3sina+sina^2-2sina+1
=sina^2+sina+1
=2不懂的欢迎追问,
因为sina+sina^2=1 所以sina=1-sina^2
3cosa^2+cosa^4-2sina+1
=3(1-sina^2)+(1-sina^2)^2-2sina+1
=3sina+sina^2-2sina+1
=sina^2+sina+1
=2不懂的欢迎追问,