1. Suppose that one inner angle of a triangle is x degrees, the other angle is 3X/2, the first angle is 5X/4, and x+3X/2+5x/4 = 180. The solution shows that x is 48 degrees, 3x/2 is 72 degrees, and 5x/4 is 60 degrees.

2. Right triangle.

Connecting the vertices opposite to the third side, this line divides the triangle into two, and the middle vertical line divides these two into four, respectively proving that the two triangles divided by the middle vertical line are congruent, and one angle of this big triangle is equal to one angle of another triangle that is congruent with him, and so is the other pair. Then the sum of the two angles of a big triangle is equal to the sum of the two angles that are congruent with him, and the two angles that are congruent with him are 180 degrees.

I'm exhausted. Oh, my God, there are no photos. You must choose me.