the answer:
cot(theta)=1.5, to find theta, cot(theta)=1.5 implies theta= arc cot (1.5)
but we kknow that cot(theta) = 1 / tan(theta), this implies
1 / tan(theta) =1.5, and tan(theta) = 1 / 1.5 = 0.6
and theta is in quadrant 3, costheta and sintheta are negatives
so tan(theta) is positive,
tan(theta) = 0.6, therefore, (theta) = arctan ( 0.6)= 30.9°
finally (theta) = 30.9°
