Area Learning Intentions Calculate the area of a square, rectangle and triangle

Definition Part of a two dimensional surface enclosed within a specified boundary or geometric figure

Finding an area Area is described in terms of the number of unit squares that fit inside or cover a shape. This is an area of 1 square unit This is an area of 2 square units

Irregular shapes The area of any shape can be found by counting the number of unit squares inside. This shape has an area of 12 square units

Regular shapes For many shapes there are formulae that help you count the square units. Squares Rectangles Triangles Circles These include Any there are many more

Area of a rectangle Here is a rectangle. It can be covered with 6 square units It has an area of 6 square units

Area of a rectangle If the size of the rectangle is known the area can be calculated using the formula Area = length x width

Here is another rectangle. This time the squares are not shown Here is another rectangle. This time the squares are not shown. The area is found using the formula Area = Length x width

The area is 20 square units. If the units are in centimetres then the area is 20 square Centimetres, written as 20cm2 If the units are in metres then the area is 20 m2

Questions for you to try Make a note of your answers before you proceed. Find the area of a rectangle of size 3 cm by 6 cm Find the area of a rectangle 5 cm by 2 cm Find the area of a rectangle 7 cm by 8 cm Click to see answers

Answers 18 cm2 10 cm2 56 cm2 Find the area of a rectangle of size 3 cm by 6 cm Find the area of a rectangle 5 cm by 2 cm Find the area of a rectangle 7 cm by 8 cm

Area of a square If you were Ok with rectangles squares are easy The rectangle area formula can be changed Rectangle area formula = Length x width L And becomes Area of a square = Length x Length L

Area of a square Example 3 Find the area of a square with sides 3 3 Area = length x length

Area of a square Example Find the area of a square with sides 3 Area = length x length Area is 9 square units

Questions for you to try Make a not of your answers before you proceed. Find the area of a square of size 6 cm by 6 cm Find the area of a square 5 cm by 5 cm Find the area of a square 7 cm by 7 cm Click to see answers

Answers 36 cm2 25 cm2 49 cm2 Find the area of a square of size 6 cm by 6 cm Find the area of a square 5 cm by 5 cm Find the area of a square 7 cm by 7 cm

Area of a Triangle These two triangles are identical

Area of a Triangle These two triangles are identical

Area of a Triangle These two triangles are identical

Area of a Triangle These two triangles are identical

Area of a Triangle These two triangles are identical

Area of a Triangle These two triangles are identical

Area of a Triangle These two triangles are identical

Area of a Triangle These two triangles are identical

Area of a Triangle Together they make a rectangle. The area of each triangle is half of the area of the rectangle. This gives us a formula for The area of a triangle. Area = ½ Length X height An alternative way of writing this is Area = ½ base X height

Area of a Triangle Example Find the area of a triangle with base 4 cm and height 5 cm 5 Area = ½ base X height 4 Area = ½ x4 x 5 Area = 10 cm2

Questions for you to try Make a note of your answers before you proceed. Find the area of a triangle of base 6 cm and height 6 cm Find the area of a triangle of base 5 cm and height 5 cm Find the area of a triangle of base 7 cm and height 7 cm Click to proceed

Answers Find the area of a triangle of base 6 cm and height 6 cm