ΔABC is similar to ΔXYZ. If XY=n, ZY=2n−1, BC=7​, and AB=4​, find n and ZY.

Question

I have no idea how to do this. I got a negative fraction, and feel like it's wrong.

Answer 1

XY = n

ZY = 2n-1

BC = 7 = CB

AB = 4

ABC is similar to XYZ

XY/AB = n/4

ZY/CB = (2n-1)/7

n/4 = (2n-1)/7

8n-4 = 7n

n = 4

ZY = 2n-1 = 8-1 = 7

ZY = 7

(it's all as easy as ABC, or XYZ) Just set ratios of similar sides = each other.