Areas Formulas

Area: Area is the amount of surface the two- dimensional shape covers. It is measured in square units.

Square: A square has two pairs of parallel sides, four right angles, and all four sides are equal. Since all the four sides are equal therefore the formula for finding the area of a square = side x side or side2. In the given diagram the side of a square is represented by symbol a. Therefore the area of a square:

Area of square = a2

Rectangle: A rectangle has two pairs of opposite sides parallel, and four right angles. Unlike square the length and width of a rectangle differ. The formula of rectangle is length x width. In the given diagram the length is represented by symbol a and width of a rectangle by symbol b

Volume of rectangle = a x b

Parallelogram: A parallelogram has two parallel pairs of opposite sides. The formula to calculate the area of a parallelogram is base x height. In the given picture the base of a parallelogram is represented by symbol b and the height by a symbol h

Area of a parallelogram = b x h

Trapezoids: Trapezoids are kind of geometrical figures that only have one pair of parallel sides. The formula for finding the area of trapezoid = ½ x h x (a+b) where h is the height of trapezoid, a is the length of top and b is the length of a bottom.

Area of a trapezium = h/2 (a + b)

Circle: A circle is a set of those points in a plane which are at a constant distance from a fixed point in the plane. The fixed point is called the centre and the constant distance of every point on the circle from its centre is called the radius of the circle. The formula for area of a circle is r2 where r is the radius of a circle and the value of (called pi) = 22/7 or ( = 3.141592…)

Area of a circle = r2

Triangle: A triangle has three sides and three angles and the three angles always add upto 180°. The formula for finding the area of a triangle is ½ x b x h where b refers to base and h refers to height of a triangle.

Area of a triangle = ½ (b x h)

Equilateral Triangle: In an equilateral triangle all the three sides are of same length and each angle measures 60°. The formula for finding the area of an equilateral triangle is:

Since all the sides are same in an equilateral triangle the side is marked by symbol a.

Heron’s Formula: A method for calculating the area of a triangle when you know the length of all three sides. Let a, b, c be the length of the sides of a triangle.

The area is given by sqrt[s(s-a)(s-b)(s-c)] when s = (a+b+c)/2

The formula can be re-written as: