\(\frac{1}{\cot ^{2}a} \frac{1}{1 \tan ^{2}a}=\frac{1}{1 \sin ^{2}a} \frac{1}{\csc ^{2}a}\)

请输入您的数学问题…… \(\frac{1}{\cot ^{2}a} \frac{1}{1 \tan ^{2}a}=\frac{1}{1-\sin ^{2}a}-\frac{1}{\csc ^{2}a}\)

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