证明:(tan^2)x-(sin^2)x=(tan^2)x(sin^2)x

问题描述:

证明:(tan^2)x-(sin^2)x=(tan^2)x(sin^2)x

左边=sin²x/cos²x-sin²x
=sin²x(1/cos²x-1)
=sin²x(1-cos²)/cos²x
=sin²x*sin²x/cos²x
=sin²xtan²x=右边
命题得证

Notice thattan²(x) = sin²(x) / cos²(x) .Using this on the right-hand side of the equation and gathering into a common fraction,we gettan²(x) - sin²(x) = (sin²(x) / cos&su...