已知tanx=1/4,则cos2x+sin^2x的值为
问题描述：
已知tanx=1/4,则cos2x+sin^2x的值为
答
cos2x+sin(^2)x=cos(^2)x
=(cos(^2)x/cos(^2)x+sin(^2)x)=(tan(^2)x/1+tan(^2)x)
=((1/4)(^2)/1+(1/4)(^2))=1/17
答
cos2x+sin^2x
=(cos²x-sin²x)+sin²x
=cos²x
=cos²x/(cos²x+sin²x)
=1/(1+tan²x)
=1/(1+(1/4)²)
=16/17
答
依然是齐次式求值.
cos2x+sin^2x
=(cos²x-sin²x+sin²x)/1
=cos²x/(sin²x+cos²x)
=1/(tan²x+1)
=16/17