Question

高一数学计算化简

Answer 1

左边=(sin^2/cos^2)*sin^2=(1-cos^2)*sin^2/cos^2
=sin^2/cos^2-sin^2=tan^2-sin^2=右边

Answer 2

如图三角形中，（tanasina）^2=(m/n)^2*m^2=m^4*/n^2

(tana)^2-(sina)^2=(m/n)^2-m^2=m^2(1-n^2)/n^2

由勾股定理：1-n^=m^2,m^2(1-n^2)/n^2=m^4/n^2

所以得证