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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.

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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.

INTERESTING FACTS:

  • Normally, all sides are not equal. However, when they are, the rectangle is said to be a square.
  • Because a rectangle is a parallelogram like a rhombus or square, opposite sides are parallel, and opposite angles are equal.
  • 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.


TRADITIONAL FORMULA

AreaRectangle = height x width

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

DEFINITIONS:

  • The HEIGHT is a straight line that is represented by the longest distance from top to bottom of a shape. The height is ALWAYS a perpendicular line from the tallest point of the shape to the base. NOTE: The HEIGHT is sometimes referred to as LENGTH.
  • The WIDTH is a straight line that is represented by the longest distance from left to right of a shape.

THINKING INSIDE THE BOX METHOD

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.


KEY: Since the shape is a rectangle, simply use the rectangle formula (height x width) to calculate its area. IMPORTANT NOTE: The rectangle formula is used as a KEY formula for many other shapes. See STEP-BY-STEP SOLUTION for detail example.

STEP-BY-STEP SOLUTION

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

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

AreaRectangle = 4 in x 6 in = 24 in2

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.