Can someone help me, I don't understand this. There are 3 parts to this question. Part A, Part B, and Part C.
Ken wants to make a triangular sunshade to cover his deck. The shade is made of two identical right triangles. Based on this, Answer Parts A, B, and C below.
(Go to my profile to see Part A)

Part B:
Ken decides to increase the length of the 15-foot side to 18 feet and decrease the overall length to 20 feet. What is the new height of the shade?
SHOW ALL YOUR STEPS FOR FULL CREDIT!