There are many ways to prove verticality in junior high school mathematics, mainly the following. The first is to prove that this triangle is a right triangle according to the inverse theorem of Pythagorean theorem, so it has a right angle. The second is that the angles corresponding to congruent triangles are equal according to the congruence of triangles, so the angles corresponding to right angles are also right angles. The third is to prove the right angle according to the parallel line theorem, that is, the parallel isosceles angles of two straight lines are equal, the parallel internal angles of two straight lines are equal, and the two straight lines are complementary.