Theorems Dealing with Rectangles, Rhombuses, Squares Rectangle Definition: A rectangle is a parallelogram with four right angles. Properties:Rectangle has all of the properties of the parallelogram. 4 right angles diagonals congruentUsing the definition, the properties of the rectangle can be "proven" true and become theorems. When dealing with a rectangle, … [Read more...] about Theorems Dealing with Rectangles, Rhombuses, Squares