Chứng minh: (1+cos x)/sin x – sin x/(1+cos x) = 2cot x

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Môn Toán Amity 4 years 2021-04-19T05:10:11+00:00 2021-04-19T05:10:11+00:00 1 Answers 11 views 0

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Captcha* Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )

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Ladonna · Answer 1 · 2021-04-19T05:11:47+00:00

Ladonna

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2021-04-19T05:11:47+00:00 April 19, 2021 at 5:11 am

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$V T = \frac{1 + \cos x}{\sin x} - \frac{\sin x}{1 + \cos x}$

$= \frac{(1 + \cos x)^{2} - \sin^{2} x}{\sin x (1 + \cos x)}$

$= \frac{1 + 2 \cos x + \cos^{2} x - \sin^{2} x}{\sin x (1 + \cos x)}$

$= \frac{2 \cos x + 2 \cos^{2} x}{\sin x (1 + \cos x)}$

$= \frac{2 \cos x (1 + \cos x)}{\sin x (1 + \cos x)}$

$= \frac{2 \cos x}{\sin x}$

$= 2 \cot x$

$= V P$