Question

What is the value of `cos(-pi/4)`?

Answer 1

`sqrt2/2`

Explanation:

`-pi/4` is the same a `(11pi)/4`

This is a `45^o` with respect to the `x-`axis.

This angle is in the `IV` quadrant where `cos` is `+`

The `cos` of a `45^o` and is `sqrt2/2`