Rectangles

Part of the Polygons & Quadrilaterals section of Coddy's Geometry journey. Lesson 20 of 59.

A rectangle is a quadrilateral with four right angles. Its neighbouring angles are all 90° + 90° = 180°, so its opposite sides are parallel: every rectangle is a parallelogram. Its opposite sides are equal too.

$Rectangle ABCD with AB = 7 and BC = 3$

Here AB = 7 and BC = 3, so CD = 7 and DA = 3, by the rule Opposite sides of a rectangle. Then the perimeter, the distance round the edge, is $7+3+7+3 = 20$ .

To ask the board for the perimeter, tap inside the rectangle and choose Perimeter. It needs every side known first.

Challenge

ABCD is a rectangle with AB = 9 and BC = 4. Find the missing sides and then the perimeter of ABCD (tap inside the rectangle for it), then press Check.

Try it yourself

$Find the marked part of the figure$

Find the marked part of the figure

All lessons in Polygons & Quadrilaterals

2Regular Polygons

Regular Polygons Inside a Regular Polygon Recap: Regular Polygons

5Rectangles, Rhombi, Squares

RectanglesThe Diagonal of a Rectangle Rhombus Angles Squares Recap: Special Parallelograms

8Area of Parallelograms

Area of a Rectangle A Side from the Area Slide the Top Area of a Parallelogram Recap: Parallelogram Area

11Polygon Chases

Parallel Sides in a Pentagon Marks, Not Looks Pentagon with x Regular Shapes Together Recap: Polygon Chases