A quadrilateral is a shape which has 4 straight sides. A quadrilateral can sometimes be called:
● ● a quadrangle (‘four angles’), so it sounds like ‘triangle’
a tetragon (‘four’ + ‘polygon’), so it sounds like ‘pentagon, hexagon,’ etc.
Consider a circle with twelve evenly-spaced dots around it, as in the diagram on the right.
Redraw this circle.
How many diff erent quadrilaterals can be made by joining the dots on the circle? Name as many of the quadrilaterals you have drawn as you can.
23.1 Rectangles and squares
By the end of this section you should be able to: ● fi nd the area and perimeter of a rectangle ● construct a rectangle
Revision of squares and rectangles
Unit 15 covered a lot of the basic skills required for this unit. Make sure you have a good understanding of Unit 15, as you will need those skills as you work through this unit.
Square Four sides are equal in length Opposite sides are parallel All angles are right angles ( 90° ) Perimeter = length + length + length + length = 4 (length) = 4l
Area = length × length = l2 Has four axes of symmetry