# Math Help - Examining a Curve - # 4

1. ## Examining a Curve - # 4

First of all finding the critical numbers is a problem for this one:

$f(x) = 3\sin(x) + 3\cos(x)$

$f'(x) = 3\cos(x) + [-3\sin(x)]$

$f'(x) = 3\cos(x) - 3\sin(x)$ Next move, hint?

2. ## Re: Examining a Curve - # 4

Originally Posted by Jason76
First of all finding the critical numbers is a problem for this one:

$f(x) = 3\sin(x) + 3\cos(x)$

$f'(x) = 3\cos(x) + [-3\sin(x)]$

$f'(x) = 3\cos(x) - 3\sin(x)$ Next move, hint?
Hello,

I assume that you want to solve for x

$3\cos(x) - 3\sin(x) = 0$

If so:

$3\cos(x) - 3\sin(x) = 0~\implies~1 = \frac{3 \sin(x)}{3 \cos(x)} = \tan(x)$

and therefore:

$x = \tan^{-1}(1)$