Geometry

Question Analysis:
Tests understanding of parallelogram properties in coordinate plane.

Key Concept Explanation:
In parallelograms, midpoints of diagonals coincide (midpoint congruence).

Step-by-Step Solution:
Calculate midpoint of WY:
((1 + 6)/2, (2 + 3)/2) = (3.5, 2.5)
Let Z = (a,b). Midpoint of XZ must equal WY's midpoint:
((4 + a)/2, (5 + b)/2) = (3.5, 2.5)
Solve:
(4 + a)/2 = 3.5 → a = 3
(5 + b)/2 = 2.5 → b...