(3sin a-cos a)/(2sin a+cos a)分子分母同时除以cos a
=(3sin a/cos a-cos a/cos a)/(2sin a/cos a+cos a/cos a)
=(3tan a-1)/(2tan a+1)
=(3*2-1)/(2*2+1)
=1你能不能把tan cos sin之间相互转化的公式配图私信我？我给20分tana=sina/cosacosa=sina/tanasina=cosa*tana就这点？是