I took notes in class on this theorem, but still don't understand how to do it. Can someone explain how this works/what to do?
What you have are three similar right triangles. The tedious part is figuring the correct correspondences.
Here is one $\Delta ACB \simeq \Delta ADC$ .
Can you find two more?
Then read off the corresponding proportionals and cross multiply.
You can prove by using pythagoras' theorem for the big triangle and the two smaller triangles.
and you can prove that and by using and pythagoras' theorem for the smaller triangles
Last edited by Shakarri; June 1st 2014 at 12:24 PM.