Giúp mình câu 2a với Thanks ❤️❤️ Question Giúp mình câu 2a với Thanks ❤️❤️ in progress 0 Môn Toán Trúc Chi 5 years 2021-05-16T13:54:40+00:00 2021-05-16T13:54:40+00:00 1 Answers 33 views 0
Answers ( )
$\quad \dfrac{1 -2\sin^2x}{\sin^2x\cos^2x}$
$=\dfrac{\cos^2x +\sin^2x- 2\sin^2x}{\sin^2x\cos^2x}$
$=\dfrac{ \cos^2x-\sin^2x}{\sin^2x\cos^2x}$
$=\dfrac{\cos^2x}{\sin^2x.\cos^2x} – \dfrac{\sin^2x}{\sin^2x.\cos^2x}$
$=\dfrac{1}{\sin^2x} – \dfrac{1}{\cos^2x}$
$= \cot^2x + 1 – (\tan^2x +1)$
$=\cot^2x – \tan^2x$