 Measurement Area    Back to Measurement Units

Area: The area of a figure is the amount of space inside that shape.
The units of area are square units.(eg. mm2, cm2, m2)

We can use the formulae to find the areas of basic shapes.

 Shape Area (A) Square A = l 2    where l is the length of a side. Rectangle A = l ū w  where l is the length, w is the width Parallelogram A = b ū h  where b is the base length, h is the height. Triangle A = Į b ūh  where b is the base length, h is the height. Trapezium A = Į (a+b)h  where a and b are the side lengths of the parallel sides, h is the height. Rhombus A = Į aū b    where a and b are the lengths of the diagonals Kite A = Į aū b    where a and b are the lengths of the diagonals Circle Area of Composite figures: To find the area of a composite figure, first you split up the composite figure into simpler shapes(eg: shapes like squares, rectangles, triangles, circles etc.) and then find the areas of each of the shapes and add them up.
The units of area are square units.(eg. mm2, cm2, m2)

Example

 Example 1. Let's find the area this figure. To find the area of the figure, we need to add the areas of  Fig.(a),Fig.(b) and Fig.(c). First we need to identify the shapes. (a) and (b) are rectangles and (c) is a triangle. Then, we can use the formula to find the area. Area of a rectangle  = length  ū width Area of a triangle    =  Į base ū height     where base =3,  height =2 Area of Fig.(a)   =  6 ū 4     =   24 Area of Fig.(b)   = 4  ū 2       =    8 Area of Fig.(c)   = Į ū 3 ū 2 =   3 Total area          = 24 + 8 + 3 = 35 square units     Example 2. Find the area of the shaded part . We want to find the area of the shaded part. First we need to identify the shapes.We have a rectangle and a circle. Then write down the formulae for areas of these shapes. Rectangle: A = l ū w  where l is the length,            where l = 26cm ,   w = 10cm                  w is the width. Circle: diameter of the circle     = 5 cm,     radius = Į of 5  = 2.5cm Area of the circle           = 3.142 ū 2.5 ū 2.5                                      = 19.6375 cm2                                      = 19.6 cm2      (rounded off to one decimal place.) Area of the rectangle     = 26 ū 10 cm2                                      = 260 cm2 Area of the shaded part = Area of the rectangle - Area of the circle                                     =   260 - 19.6                                     =   240.4 cm2 Have a Go

 Problem 1 Find the area of this figure.  Problem 2           Find the area of this figure.  Practice Questions

 Question 1 Find the area of the triangle. answer 63.2 square metres Question 2 Find the area of the flower bed. answer 3.3 square metres Solution 1 Area of (a) = 10 ū 6 = 60 Area of (b) = Į ū 10 ū 6 = 30 Area of the figure = 60 + 90                            = 150square units       back to Have a Go To find the area of the figure, first we need to identify the shapes. Fig.(a)   rectangle Fig.(b)   triangle Then we have to use the formula to calculate the area of each shape. Rectangle:   A = l ū w  where l is the length,                   w is the width, A is the area. where l = 10units ,   w = 6units                 Triangle: A = Į b ūh  where b is the base length,                      h is the height, A is the area. where b= 10 units,  h= 6 units Substitute the values and calculate the areas and add them together to find the total area. Solution 2 Area of (a) =12 ū 6 = 72 cm2 Area of (b) = (3.142 ū 3 ū 3) „ 2                   = 14.139 cm2                   = 14.1 cm2 (rounded off to one                                          decimal place.) Total area = 72 + 14.1 = 86.1 cm2 back to Have a Go Identify the shapes. Fig.(a) ~ rectangle Fig.(b) ~ semicirle Use the formulae to calculate the areas. Rectangle: A = l ū w  where l is the length,                   w is the width, A is the area. Area of a Circle: Area of the semi circle = area of the circle „ 2 Area of the semi circle = (3.142 ū 3 ū 3) „ 2 