
Area of a rectangle = $length × breadth$ 
Perimeter of a rectangle = $2 (length + breadth)$ 

Area of a square = $side^2$ 
Perimeter of a square = $4 × side$ 

Area of a circle = $π × radius^2$ 
Perimeter (Circumference) of a rectangle = $2 × π × radius$ 

Area of a circle = $π × radius^2 × C/360$ 
Perimeter of a sector = $(2 × radius) + $ (Length of arc AB) 

Area of a triangle = $ 1/2 × height × base$
Hero's formula  A greek mathematician, Hero, gave the formula of area of triangle as follows: 
Perimeter of a triangle = sum of the lengths of all the three sides 

Area of a pentagon = $ 5 × (1/2 × height × base)$ 
Perimeter of a pentagon = sum of the lengths of all the five sides 