# What is the equation of the normal line of #f(x)= secxtanx# at #x = pi/8#?

##### 1 Answer

Apr 16, 2017

#### Explanation:

It helps to know some trig derivatives:

First, take the derivative of

Simplify:

Plug in

This is the slope of the tangent line but we need the slope of the normal line. Take the negative reciprocal of

Now we need a point. Plug in

Now we have the point