Giúp mình câu 2a với Thanks ❤️❤️ Question Giúp mình câu 2a với Thanks ❤️❤️ in progress 0 Môn Toán Ngọc Diệp 5 years 2021-05-17T02:17:55+00:00 2021-05-17T02:17:55+00:00 1 Answers 19 views 0
Answers ( )
$\quad \dfrac{1 -2\cos^2x}{\sin^2x\cos^2x}$
$=\dfrac{\sin^2x + \cos^2x – 2\cos^2x}{\sin^2x\cos^2x}$
$=\dfrac{\sin^2x – \cos^2x}{\sin^2x\cos^2x}$
$=\dfrac{\sin^2x}{\sin^2x.\cos^2x} – \dfrac{\cos^2x}{\sin^2x.\cos^2x}$
$=\dfrac{1}{\cos^2x} – \dfrac{1}{\sin^2x}$
$= \tan^2x + 1 – (\cot^2x +1)$
$=\tan^2x – \cot^2x$