Answer:
Step-by-step explanation:
If the given is the parallelogram, its opposite sides are parallel.
<u>It means the slopes of those lines are equal:</u>
- AB ║ CD
- (y₂ - y₁)/(x₂ - x₁) = (y₄ - y₃)/(x₄ - x₃)
If the parallelogram is a rectangle, then its adjacent sides are perpendicular.
<u>It means the product of slopes of those lines is - 1:</u>
- CD ⊥ AD or CD ⊥ BC
- (y₄ - y₃)/(x₄ - x₃) × (y₄ - y₁)/(x₄ - x₁) = - 1
or
- (y₄ - y₃)/(x₄ - x₃) × (y₃ - y₂)/(x₃ - x₂) = - 1
The matching choice is combination of AB ║ CD and CD ⊥ BC.
Correct choice is C
