Olympiad Maths Prep

Track / Stage 5 / 80 of 400 #680 of 2000

Problem 680

AIME late
Geometry Difficulty 5.2 Prove it

## Task 5 - 040815

The following statement is to be proven:

If in a triangle a median is half as long as the corresponding side, then the triangle is a right triangle.

This one wants a proof. Work it on paper, read the official solution, then mark yourself honestly — the ladder only means something if the record is true.

Official solution

According to the conditions of the sentence, the vertices of the triangle lie on the Thales circle over AB\overline{A B}, if aca_{c} is the median.

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.