AREA AND PERIMETER 

Perimeter

Perimeter is the distance round the boundary of a closed figure.

Area

Area is the amount of space within a closed figure and is usually measured in square units.

Areas and Perimeters of Common Shapes
Shape	Area	Perimeter
Figure A is a rectangle	Area of rectangle = Length x Breadth	Perimeter of rectangle = 2(Length + Breadth)
Figure B is a square	Area of square = Length x Length	Perimeter of square = 4 x Length
Figure C is a triangle	Area of triangle = Base x Height         2	Perimeter of triangle XYZ = XY+ YZ+ XZ
Figure D is a circle	Area of circle = pi x radius x radius (pi = 22/7 or 3.14 approx.)	Perimeter of circle = 2 x pi x radius or pi x diameter (pi = 22/7 or 3.14 approx.)

 

Examples:

1. Find the perimeter of the figure given below.

 AB = FE+ DC
= 8+8
= 16cm

CB = DE + FA
= 6 + 6
= 12cm

Perimeter of the figure =6+8+6+8+12+16
= 56 cm

 

2. ABCD is a rectangle. What is the area of the shaded part?
 
 
Area of rectangle = 20 x 15
= 300 cm²

Area of unshaded triangle = 20 x 15
                                                2
= 150 cm²

Area of shaded part = 300 - 150
= 150 cm²

 

3. Find the area of the shaded part. (Take pi to be 22/7)
 
 

Radius of circle = 14/2
= 7 cm 

Area of semicircle = ½ x 22/7 x 7 x 7
= 77 cm²
 

3. Find the perimeter of the quadrant. (Take P to be 3. 14)
 
   

Diameter of circle = 7 x 2
= 14 cm

Circumference of quadrant = 1/4 x 3.14 x 14
= 10.99 cm

Perimeter of quadrant = 10.99 +7 + 7
= 24.99 cm