来自丁利的问题
三角函数恒等式急tan^2a-cot^2a/sin^2a-cos^2a=sec^2a+csc^2a(注:分子在前分母在后
三角函数恒等式急
tan^2a-cot^2a/sin^2a-cos^2a=sec^2a+csc^2a
(注:分子在前分母在后
1回答
2020-02-29 14:25
三角函数恒等式急tan^2a-cot^2a/sin^2a-cos^2a=sec^2a+csc^2a(注:分子在前分母在后
三角函数恒等式急
tan^2a-cot^2a/sin^2a-cos^2a=sec^2a+csc^2a
(注:分子在前分母在后
(tg^2a-ctg^2a)/(sin^2a-cos^2a)
=(sin^2a/cos^2a-cos^2a/sin^2a)/(sin^2a-cos^2a)
=(sin^4a-cos^4a/sin^2a*cos^2a)/(sin^2a-cos^2a)
=(sin^2a+cos^2a)/(sin^2a*cos^2a)
=sec^2a+csc^2a