Question

1. What is the tangent line of y = cos x at x = /4?

Answer 1

Slope of the tangent is, $m = \frac{dy}{dx} = - \sin(x)$

at x = $\frac{\pi}{4}$, m = $- \frac{1}{ \sqrt{2} }$

At x = $\frac{\pi}{4}$, y = $\frac{1}{ \sqrt{2} }$

Equation of tangent is,

$m= \frac{y-y1}{x-x1}$