# Finding the angle

• July 12th 2010, 04:06 PM
Finding the angle

A circle with a radius of 1.
the point P giving the co-ordinates (-√3/2 , -1/2)

So it rotates through the 1st and 2nd quadrant and ends in the 3rd at point P. The angle in the third I'm unsure of. I know that its already 180 degrees.

would i solve the 3rd quadrant angle by finding it using cos θ A/H

so it would be (-√3/2)/1 = -1.225?

Thanks for any help.
• July 12th 2010, 04:36 PM
skeeter
$\displaystyle \theta = \frac{7\pi}{6}$

recommend you learn the unit circle ...

http://www.math.uky.edu/~rbrown/cour...nit_circle.gif
• July 12th 2010, 04:58 PM