# Rectangle

*(Jump to Area of a Rectangle or Perimeter of a Rectangle)*

A rectangle is a four-sided flat shape where every angle is a right angle (90°).

the little squares in each corner mean "right angle"

Each internal angle is 90° | |

Opposite sides are parallel and of equal length (so it is a Parallelogram). |

Play with a rectangle:

images/geom-quad.js?mode=rectangle

## Area of a Rectangle

Area = a × b |

### Example: A rectangle is 6 m wide and 3 m high, what is its Area?

Area= 6 m × 3 m

=

**18 m**^{2}## Perimeter of a Rectangle

The Perimeter is the distance around the edges.

The Perimeter is Perimeter = 2(a+b) |

### Example: A rectangle is 12 cm long and 5 cm tall, what is its Perimeter?

Perimeter = 2 × (12 cm + 5 cm)

= 2 × 17 cm

=

**34 cm**## Diagonals of a Rectangle

A rectangle has two diagonals, they are equal in length and intersect in the middle. |

A diagonal's length is the Diagonal "d" = √(a |

### Example: A rectangle is 12 cm wide, and 5 cm tall, what is the length of a diagonal?

d= √(12

^{2}+ 5^{2})= √(144 + 25)

= √169

=

**13 cm**## Golden Rectangle

There is also a special rectangle called the Golden Rectangle:

9091, 9092, 9093, 9094, 9095, 9096, 9097, 9098, 9099, 9100