1. Circle – Formulas
Radius of the circle is generally denoted by letter R.
Diameter of the circle D = 2 × R
Circumference of the circle C = 2 ×  × R ( = 22/7)
Area of the circle A =  × R2

2. Quadrilaterals – Formulas
Rhombus
Square
Rectangle
Area = lb
Perimeter = 2(l+b)
l = length
b = breadth
Area = (d1d2)/2
Perimeter = 4s
s = side
d1,d2 = diagonals
Area = s2
Perimeter = 4s
(s = side)
Kite
Trapezium
Parallelogram
Area = ba
Perimeter = 2(l + b)
(b = base/breadth
a = altitude
l = length)
d1, d2 = diagonals

3. Triangles – Formulas Area of a triangle = ½ × base × height
Perimeter of an equilateral triangle = 3s (s = side)
Area of an equilateral triangle

4. Solids – Formulas