化简(sin^2a-tan^2a)*(sin^2a*tan^2a)
问题描述：
化简(sin^2a-tan^2a)*(sin^2a*tan^2a)
答
(sin^2a-tan^2a)(1-cos^2a)tan^2a
=(sin^2a-tan^2a)(tan^2a-sin^2a)
=-(sin^2a-tan^2a)^2
答
(sin^2a-tan^2a)*(sin^2a*tan^2a)
=sin^2a(1-sec^2a)*(sin^2a*tan^2a)
=-(sin^2a*tan^2a)^2
答
化简(sin^2a-tan^2a)*(sin^2a*tan^2a)=(1-cos^2a-tan^2a)*[(1-cos^2a)tan^2a]=[1-1/(1+tan^2a)-tan^2a]*[1-1/(1+tan^2a]tan^2a=[tan^2a/(1+tan^2a)-tan^2a][tan^2a/(1+tan^2a]tan^2a