When can a parallelogram also be called a rectangle?

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Step-by-step explanation:

A rectangle is is a type of parallelogram with four right angles.

Answer: A parallelogram can be called a "Rectangle" when all its angles measure 90° (right angles).

Step-by-step 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).