Perimeter/Area/Volume

Learners will be able to:1. Describe the terms perimeter, circumference, area

and volume2. Calculate perimeter, circumference, area and

volume

Perimeter/Circumference

• The perimeter of a shape is the total length of its boundary.

• For a rectangle the perimeter is P = 2(l+w), where l is the length and w is the width.

Perimeter/Circumference

• The perimeter of a circle is called the circumference.

• The circumference, C, of a circle can be written in two ways:

• C = πd where d = diameter• C = 2πr where r = radius

π/Pi

• π is a special number, equal to the ratio of the circumference of a circle to its diameter.

• π is an irrational number, which means it cannot be written as a fraction.

• π is approximately equal to 3.142.• The π key on your calculator gives π to more

places of decimals 3.141592654

Example 1

• A circular pond, 3.6 metres in diameter, has a fence around it, at a constant distance of 0.6 metres from the edge. Find the length of the fence.

Area

• Area of a shape is a measure of the amount of space it covers.

• For a rectangle/square the area is l x w• For a circle the area, A, is given by the

formula: A = πr², where ‘r’ is radius. • Diameter of a board is 45 cms. What is the

area of the board? (Use BIDMAS rule)• Answer: 1590 m²

Example

Volume

• The volume of a 3-D shape is a measure of the amount of space it occupies.

• The volume of a cuboid is l × w × h where l = length, w = width and h = height.

Volume

• The volume, V, of a cylinder is: V = πr2h• where r is the base radius and h is the height.

Example

3-D Problems

Answer