Final answer:
To prove that angle CXY is congruent to angle BXY, we can use the fact that line AC is congruent to line AB.
Step-by-step explanation:
To prove that angle CXY is congruent to angle BXY, we can use the fact that line AC is congruent to line AB. This implies that triangle ACX is congruent to triangle ABX (by Side-Side-Side congruence). Since corresponding angles of congruent triangles are congruent, we have angle CXY congruent to angle BXY.