Question

http://i.imgur.com/wNfN48a.png

how to prove triangle ICR is equal to triangle ISU?

given: < 1 = < 4, CU = RS, IC = IS

Answer 1

it will take a few steps
side IC = side IS (given)
angle <2 = angle <3 (this will take a few steps to prove)
side CR= side US (this will take a few steps)

then by side-angle-side the two triangles are congruent.