1. Maths Unit 3 – Area & Perimeter
Finding the perimeter and area by counting
To find the perimeter of the shape to the right, you count
around the outside of the shape. The perimeter of this shape is 26cm.
To find the area of the shape to the right, you count the number of squares inside the shape. The area of this shape is 19cm².
= 1cm²
Working with circles
Formulae you need to know to find the area of different shapes
The diameter = 2 x radius
The radius = ½ of the diameter
π = 3.142
Key words and definitions
Perimeter – The distance around the outside of a shape
Area – Space inside a 2D shape
Circumference - The distance around the outside of a circle
Diameter – A straight line passing from one side to the other of a circle through the centre
Radius – A straight line passing from the centre to the circumference of the circle
Parallelogram – A quadrilateral with two pairs of parallel lines
Trapezium – A quadrilateral with one pair of parallel lines