Geometry

Question Analysis:
This is a missing vertex problem for a quadrilateral where the shape must be a parallelogram.
The main focus is applying the property that diagonals in a parallelogram bisect each other.

Key Concept Explanation:
If PQRS is a parallelogram, then diagonals PR and QS must have the same midpoint.

Step-by-Step Solution:
– Find midpoint of PR:
P(1, 2), R(9, 10) → midpoint = (1 + 9)/2 , (2 + 10)/2 = (5, 6)
– Let S = (x, y); midpoint of QS must also be (5, 6)
Q(7, 5) and S(x, y):
(7 + x)/2 = 5...