QUADRILATERAL

Quadrilateral > Parallelogram > Rectangle

RECTANGLE

Definition

A rectangle is a quadrilateral / parallelogram that has two (2) pairs of EQUAL sides with ALL four (4) RIGHT ANGLES (90°). Rectangle actually means right angle.

NOTE: Normally, all sides are not equal. However, when they are, the rectangle is said to be a square.

A right angle is an internal angle which is equal to 90°.

A drawing showing rectangle that has two pairs of equal sides with all four right angles.

NOTE: Because a rectangle is a parallelogram like a rhombus or square, opposite sides are parallel and opposite angles are equal.

INTERESTING FACT: All rectangles are parallelograms but not all parallelograms are rectangles.

It Is Helpful To Think

It is helpful to think of a RECTANGLE as a SQUARE that has been stretched horizontally, vertically, or both so that the sides are no longer the same.

A drawing showing a square being stretched into a rectangular shape.

Traditional Formula

Area_Rectangle = height x width

A drawing showing a rectangle width and height measurements with arrows.

NOTES:

The HEIGHT is a straight line that is represented by the longest distance from top to bottom of a shape.
CloThe WIDTH is a straight line that is represented by the longest distance from left to right of a shape.
The height is ALWAYS a perpendicular line from the tallest point of the shape to the base (width).

Thinking Inside The Box

If you place a RECTANGLE inside of a box (a square or a rectangle), you can imagine a rectangle as a regular or an elongated (stretched) square.

A drawing showing showing numbers inside of it that represent the square area of the rectangle.

NOTE: The rectangle formula is used as a key formula for many other shapes.

KEY: Since the shape is a rectangle, simply use the rectangle formula to calculate its area.

Example

A rectangle with a width of 6 in and a height of 4 in has an area of:

Simply use the rectangle formula (Area_Rectangle = height x width) since it is the KEY FORMULA that can be used for many shapes.

Area_Rectangle = 6 in x 4 in = 24 in²

REFERENCE: See screenshots above for graphic representations.

Memorization Tip

To help you remember the difference between a rectangle and a square, remember that a rectangle normally has two pairs of equal sides that are not equal; whereas, a square has ALL four equal sides.