$\tan^2\alpha-\sin^2\alpha.\tan^2\alpha$ $=\tan^2\alpha(1-\sin^2\alpha)$ $=\tan^2\alpha.\cos^2\alpha$ $=\sin^2\alpha$ Bình luận
$\tan^2\alpha-\sin^2\alpha.\tan^2\alpha$
$=\tan^2\alpha(1-\sin^2\alpha)$
$=\tan^2\alpha.\cos^2\alpha$
$=\sin^2\alpha$
Đáp án:
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