Answer :
tan-1(-sqrt(3)/3). The simpler term for (-sqrt(3)/3) is (-1/sqrt(3)) which has to do with the tan(-30); which is tan(-pi/6).
The inverse trig functions take numbers as inputs and spit out angles in a restricted domain. The domain for tan-1 is (-pi/2,pi/2), so the angle has to be -pi/6.
The inverse trig functions take numbers as inputs and spit out angles in a restricted domain. The domain for tan-1 is (-pi/2,pi/2), so the angle has to be -pi/6.