Trigonometric equations, help? ^^

[Wholewheat458]

Homework Statement

2 cos^2 x + cos x = 0
and
tan x = 3^1/2

Homework Equations

.. ?? Unit circle.

The Attempt at a Solution

for the first, well I tried factoring to isolate x, but it really did not work
i keep making up my own rules that end up messing with the entire equation,
i know, its not the best method
with the second, i used the unit circle (cos, sin) and the principal
that tan is = to sin/cos, but none of them are equal to the square root of 3..oy
any help would be much appreciated ^^
:shy:

 

[tiny-tim]

2 cos^2 x + cos x = 0
and
tan x = 3^1/2

Hi Wholewheat458!

(have a square-root: √ )

There's lots of ways of doing this.

Divide the first equation by cosx … that gives you cos x = 0 or -1/2.

Use sec²x = tan²x + 1 … that gives you cosx = ±1/2.

And you do know an angle with cosx = 1/2, don't you?