In math, is there a connection between the words "complementary" and "complement?"

i know that complementary angles adds up to 90 degrees, and a complement is everything that is not in one group, but is there a connection between the two?

Yes, they both in a sense mean "completing" or "opposite". A thing plus the complement of a thing add together to make the whole. In the first case, the "whole" is the whole right angle. In the second case, the "whole" is the set of all things in the system.

So yes, complement (with an e) always means something along those lines. p.s. it is totally different to the word compliment (with an i)