Area

Area is the size of the region enclosed within a plane figure. To the carpenter or carpet layer, who is concerned with the amount of material to be used, measurement of area is very important. Area is measured in square units. The most frequently used units of area are mm2, cm2 and m2. Land areas are often given in hectares (ha). 1 ha = 10 000 m2 The area of plane figures are often required to solve real world problems. Area of a Square
A square with sides of length s units has an area of A square units given by the formula
Example 1 Find the area of a square flower-bed of side 4.5 m. Solution:
So, the area is 20.25 m2.
Note: To find the area of a region enclosed within a plane figure, draw a diagram and write an appropriate formula. Then substitute the given values and use a calculator, if necessary, to obtain the required area.

Area of a Rectangle
A rectangle with length l units and width w units has an area of A square units given by the formula
Example 2 Find the area of a rectangular field 40 m long and 30 m wide. Solution:

Area of a Triangle
A triangle with base b units and height h units has an area of A square units given by the formula
Example 3 Find the area of a triangle with base 14 cm and height 10 cm. Solution:
Example 4

Perimeter

Perimeter is the distance around a closed figure. Perimeters can be measured in millimetres (mm), centimetres (cm), metres (m) and kilometres (km). These units are related as follows: Perimeters of the following figures are often required to solve real world problems.
Perimeter of a Square Recall that:
The perimeter, P, of a square is given by the formula: P = 4s where s is the length of any side of the square.
Example 1 Find the perimeter of a square paddock of side 35 m. Solution:
So, the perimeter is 140 m.

Perimeter of a Rectangle
The perimeter, P, of a rectangle is given by the formula P = 2(l + w) where l is the length and w is the width of the rectangle.
Example 2 Find the perimeter of a rectangular field of length 50 m and width 40 m. Solution:
So, the perimeter is 180 m.

Perimeter of a Triangle
The perimeter, P, of a triangle is given by the formula: P = a + b + c where a, b and c are the side lengths of the triangle.
Example 3 Find the perimeter, P, of the triangle shown. Solution: So, the perimeter is 24 cm. Example 1