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.