Practice Questions on Areas

Note: pi = 22/7

Rectangle:

Area of a rectangle = (Length * Breadth). sq.units
Length = Area/Breadth units and Breadth = Area/Length units
Perimeter of a rectangle = 2(Length + Breadth) units

Square:

Area of a square = (side)² > = (diagonal)² sq units
Permieter of a square = 4 * (side) units
Area of 4 walls of a room = 2 (Length + Breadth) * Height. sq.units

Triangle:

Area of a triangle = Base * Height/2 sq.units
Area of a triangle = (s*(s-a)*(s-b)*(s-c)) sq.units
where a, b, c are the sides of the triangle and s = (a + b + c)/2
Area of an equilateral triangle = [3* (side)² ]/4 sq.units
Radius of incircle of an equilateral triangle of side a = a/(2* 3 ) units.
Radius of circumcircle of an equilateral triangle of side a = a/(3 ) units
Radius of incircle of a triangle of area A and semi-perimeter s = A/s units

Quadrilaterals:

Area of parallelogram = (Base * Height). sq.units
Area of a rhombus = (Product of diagonals)/2 sq.units
Area of a trapezium = (sum of parallel sides) * distance between them/2. sq.units

Circle:

Area of a circle = pi * R² sq.units, where R is the radius.
Circumference of a circle = 2*pi*R.
Length of an arc = 2*pi*R*g/360 units , where g is the central angle.
Area of a sector = (1/2)*(arc x R) = pi*g*(R² )/360

Semi-circle:

Circumference of a semi-circle = pi * R units
Area of semi-circle = [(pi*R² )]/2 sq.units