Question

$y=2\tan x$ Find $\frac{dy}{dx}$ at $x=\frac{\pi }{4}$

Answer 1

$y=2\tan x\frac{dy}{dx}=2{\sec }^{2}xx=\frac{\pi }{4}\frac{dy}{dx}=2{\sec }^2\frac{\pi }{4}\frac{dy}{dx}=2(\sqrt{2}{)}^2=4$