Evaluating expressions
tan -1 (- square root of 3/3)
give answers in both radians and degrees
have answer but do not understand how to do it. assigned section without being taught as we have sub all week

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.

Iwould think that the correct answer is 8.1