An additive inverse is a number and it's positive or negative equal away from zero. Both numbers added together must equal zero. So 8 and -8 are additive inverses because they equal zero. 10.5 and -10.5 are additive inverses.
For your problem above, 1.4 is the additive inverse of -1.4 because added together they equal zero.
They must be complementary. these 2 angles MUST equal 90 degrees because there is a right angle that is 90 degrees in the triangle already and all triangles have an angle sum of 180 degrees. the answer is complementary
