Classifying figures with coordinates  Analytic geometry  High school geometry  Khan Academy  Summary and Q&A
TL;DR
To determine if a parallelogram is a rectangle, we need to check if its adjacent sides intersect at right angles.
Questions & Answers
Q: How can we determine if a parallelogram is a rectangle?
To determine if a parallelogram is a rectangle, we check if its adjacent sides intersect at right angles. If they do, then the parallelogram is a rectangle.
Q: What is the relationship between a parallelogram and a rectangle?
All rectangles are parallelograms, but not all parallelograms are rectangles. A rectangle is a special type of parallelogram where all angles are right angles.
Q: Why is it important to check if the adjacent sides of a parallelogram intersect at right angles?
Checking if the adjacent sides of a parallelogram intersect at right angles is important because a rectangle is defined by having all angles as right angles. If the adjacent sides intersect at right angles, then the parallelogram is a rectangle.
Q: What is the significance of finding perpendicular slopes in determining if a parallelogram is a rectangle?
Finding perpendicular slopes between the adjacent sides of a parallelogram indicates that the sides intersect at right angles, confirming that the parallelogram is a rectangle.
Summary & Key Takeaways

A parallelogram is a quadrilateral with opposite sides parallel.

Not all parallelograms are rectangles, but all rectangles are parallelograms.

To determine if a parallelogram is a rectangle, we need to check if its adjacent sides intersect at right angles.