Area and Perimeter


Area can be defined as the surface measured inside the boundary of a 2 - dimensional plane objects like triangle, circle, rectangle, square, … In the following diagrams, red surface denotes the area.

Area and Perimeter of Shapes

Area is measured in terms of unit squares (unit centimeter squares or unit meter squares)

Standard unit of area of plane figures is a square centimeter (cm2) or square meter(m2)

Square centimeter (cm2) is the area of planar region bounded by a square of side one centimeter.

Square meter (m2) is the area of planar region bounded by a square of side one meter.


Perimeter is the total length required to make the boundary of a 2 - dimensional plane objects such as triangle, circle, rectangle, square,… The black line denotes the perimeter.

Area and Perimeter Formulas

Area of Plane Closed Figures

Area of Triangle

Area of a triangle = $\frac{1}{2}$ x b x h square units where b is the base and h is the height

Area of Rectangle

Area of rectangle = l x w square units where l is the length and w is the width

Area of Trapezoid

Area of trapezoid = $\frac{1}{2}$ (a +b) h square units where a and b are the length of the sides of the trapezoid and h is the vertical height


Area of square = a2 square units where a is the length of the side of the square


Area of parallelogram= b x h square units where b and h are base and height of the parallelogram


Area of circle = $\pi$ x r2 square units where r is the radius of the circle

Perimeter Closed Figures

Perimeter of Square
Perimeter of square = 4a, where 'a' is a side of square.
Perimeter of Trapezoid

Perimeter of trapezoid = a + b + c + d, where a, b, c and d are sides of the trapezoid.
Perimeter of triangle : 2s = a + b + c, where a, b, c are sides of the triangle.
Perimeter of Rectangle

Perimeter of rectangle: 2a + 2b => 2(a + b).

Area and Perimeter Word Problems

Below you could see area and perimeter problems

Area and Perimeter Practice

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