We have a triangle $\triangle ABC$ where $AC = 17,$ $BC = 15,$ and $AB = 8.$ Let $M$ be the midpoint of $AB.$ What is the length of $CM$?

Let A = (0,8) B =(0,0) C = (15,0) and M = (0,4)

So CM = √ [ (15 - 0) ^2 + ( 0 - 4)^2 ] = √ [15^2 + 4^2 ] = √ [ 225 + 16] = √241 ≈ 15.52 units