How would I find this? Would I do 90- # or?

In a triangle, all the angles add up to 180 degrees. The square in the bottom left of the triangle shows that it is a right angle or 90 degrees. So you have two angles and you subtract them both from 180.

180-42-90=48

So your answer is 48 degrees.

answer: both chords and diameters have two endpoints on a circle. diameters must intersect the center of a circle.