tanx=6,1/2sin^2x+1/3cos^2x=?

1/2sin^2x+1/3cos^2x
=1/3(sin^2x+cos^2x)+1/6sin^2x
=1/3+1/6sin^2x
因为tanx=6=sinx/cosx
所以两边平方得sin^2x=36cos^2x
又sin^2x+cos^2x=1
所以sin^2x=36/37
所以1/3+1/6sin^2x
=1/3+(1/6)*(36/37)
=37/111+18/111
=55/111
懂了么
有什么不懂的可以问我