Aptitude - Area Calculation

Important Fact and Formulae

Following are important facts and formulaes used in questions for area calculations.

Rectangle/Square

• Area of a rectangle = Length x Breadth

• Length of a rectangle = Area / Breadth

• Breadth of a rectangle = Area / Length

• Perimeter of a rectangle = 2(Length + Breadth)

• Area of 4 walls = 2(length+ Breadth) x height

• Area of a Square = (side)² = 1/2(diagonal)²

Triangle

• Area of a triangle= (1/2 x Base x Height)

• △ =√{S(S-A) (S-B)(S-C)}, where S=1/2(a+b+c)

• Area of equilateral triangle = √3/4 x a²

• Radius of a in circle of an equilateral triangle of side a = a/2√3

• Radius of a circumcircle of an equilateral triangle of side a =a/√3

• Radius of in circle of a triangle= △/S, Where s=1/2(a+b+c)

Circle

• Area of a circle= πR²

• Circumference = 2πR

• Arc length= 2πRϑ/360, where ϑ is a central angle.

• Area of Sector=1/2(arc length x R) = πR²ϑ/360

• Area of Semicircle= 1/2πR²

Other shapes

• Area of a parallelogram = (base x height)

• Area of a rhombus= 1/2(product of diagonals)

• Area of a trapezium= 1/2 (sum of parallel sides) x (distance between them)

Solved Examples