Toán Lớp 9: Rút gọn: Tan²x ( 2cos²x + sin²x -1)
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Toán Lớp 9: Rút gọn: Tan²x ( 2cos²x + sin²x -1)
Giúp mình vớiii
Comments ( 1 )
= {\tan ^2}x(co{s^2}x + {\cos ^2}x + {\sin ^2}x – 1)\\
= {\tan ^2}x(co{s^2}x + 1 – 1)\\
= {\tan ^2}x.co{s^2}x\\
= \dfrac{{{{\sin }^2}x}}{{co{s^2}x}}.co{s^2}x\\
= {\sin ^2}x$