A plane is flying in the direction 290 degrees ( measured clockwise from north). Its airspeed is 800 km/ hr. The wind at the planes altitude is blowing in the direction 150 degrees ( measured clockwise from north) at 100 km/ hr. what is the true direction ( measured clockwise from north) and ground speed of the plane?

This is what i have so far

for the boat vector

$\displaystyle \vec{p} = 800 < cos 290^0, sin 290^0 > $

for the wind vector

$\displaystyle \vec{w} = 100 < cos 150^0, sin 150^0 > $

vector t for the true coarse of plane.

After multiplying and adding both cos and sin of both vectors i have:

$\displaystyle \vec{t} = < 187.013, - 701.754 > $

that would put me in the third quadrant?

i need to find the angle?

$\displaystyle \theta = tan^-1 \frac{ -701.754}{187.013} = - 76.030 ^0$

at this point do i subtract 180^0?