You can put this solution on YOUR website! i've never seen this question come up.
usually when you talk about complementary angles, the angles are assumed to be positive angles less than 90 degrees.
in order for those angles to be complementary, their sum must be equal to 90 degrees.
since a 120 degrees angle is greater than 90 degrees, then complementary is assumed not to apply.
You can put this solution on YOUR website! Complementary angles are usually defined for angles between 0 and 90 degrees. You could technically say the complement is a -30 degree angle, because the polar coordinate system allows for negative angle measures.
