First prove that ∆CBD ~ ∆ABC. Each triangle has a right triangle and each
includes angle B. The triangles are similar. You can use similar reasoning to show that ∆ACD
~ ∆ABC. To show that ∆CBD ~ ∆ACD, begin
by showing that angleACD = angle B because they are both complementary to angleDCB. Then you can use Similarity Postulates. I found the image of the triangle that was missing the question! Attached triangle.
