For all rhombi, the diagonals bisect each other at right angles. Therefore, the lengths of DM and MG are equal. Firstly let's find the length of DM, which we can calculate from Pythagorean Theorem, because we are given HM= 12 and HD= 15 and already know â–ł HMD is the right triangle.
HD^2= DM^2+ HM^2
Let's solve the equation.