to find the coordinates you'll need the cos and sin of the angle its just like with x and y:
(x,y)= (cos angle, sin angle)
to find the sin, you simply need to use these formulas:
sin² A + cos ² A= 1
sin A/ cos A= tan A
1.
sin² O + cos² O= 1
sin²O= 1- cos² O
sin²O= 1- (-9/41)²
sin²O= 1600/1681
sin O= V1600/ V1681
sin O= 40/41
2.
sin O/ cos O = tan O
(40/41)/(-9/41)= tan O
-164/9= tan O