MathLabs

Problem 4

Construct a right triangle with a given hypotenuse cc such that the median drawn to the hypotenuse is the geometric mean of the two legs.
Step 4 of 4: Verify necessity and sufficiency
The construction is valid, and every valid triangle arises this way\text{The construction is valid, and every valid triangle arises this way}
Detailed analysis

The preceding area argument proves every required triangle has altitude c/4c/4, so it must occur among these intersections. Conversely, every intersection gives a right triangle with hypotenuse cc and altitude c/4c/4, hence ab=ch=c2/4ab=ch=c^2/4 and ab=c/2\sqrt{ab}=c/2, exactly the median length.