# Simple trigonometric equation can you help?

• February 26th 2009, 01:45 PM
db5vry
Simple trigonometric equation can you help?
tan theta = - root 3 is the question, obviously I'm trying to find theta here.

I used inverse tan root 3 to get a value of 60, and then drew a trigonometric graph with active tan and got 150 and 300 for values of theta. Can anyone confirm this is right?
• February 26th 2009, 02:07 PM
skeeter
$\arctan(-\sqrt{3}) = -60^{\circ}
$

$-60^{\circ} + 360^{\circ} = 300^{\circ}$

other angle is back in quad II, 180 degrees out

$300^{\circ} - 180^{\circ} = 120^{\circ}$