1. ΔPXQ is isosceles 1. PX = XQ
2. ∠XPQ = ∠XQP 2. base angles of isosceles ΔPXQ
3. ∠XPQ = ∠XRS 3. alternate interior angles when
∥ lines PQ,SR are cut by
transversal PR.
4. ∠XQP = ∠XSR 4. alternate interior angles when
∥ lines PQ,SR are cut by
transversal QS.
5. ∠XSR=∠XQP=∠XPQ=∠XRS 5. Things = to = things are = to
each other, from steps 4,2,3
6. ΔSXR is isosceles 6. Base angles equal
7. XS = XR 7. Legs of isosceles ΔSXR are equal.
Edwin