Answer: A parallelogram can be called a "Rectangle" when all its angles measure 90° (right angles).
Explanation:
You need to remember the following definitions:
1. A quadrilateral is a polygon that has four straight sides.
2. A parallelogram is a quadrilaleral whose opposite sides are parallel and its opposite angles equal.
3. A rectangle is a quadrilateral whose opposite sides are parallel and have equal lenght. Every angle of a rectangle measure 90 degrees.
Based on this, you can conclude that a rectangle is a parallelogram.
Therefore, a parallelogram can be called a "Rectangle" when all its angles measure 90° (right angles).