Explain why two right triangles, each with an acute angle of 17°, must be similar

A right triangle is a triangle that has 1 90 degree, or "right" angle. Since there are only 3 angles, if you know 2 of the angles, you can subtract them from the total angle amount to get the third angle, which will stay the same in two right triangles if the second angle is the same. This means that they are similar.