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)

= 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