Circle Area Calculator - Enter radius and calculate the circle area

## Formula to Calculate Area and Perimeter of a Circle

Area of a Circle using Radius:

Area = πr²

r is radius and Pi value is 3.14

Radius of a Circle given its area:

Radius = square root (A / π)

A is area and Pi value is 3.14

Perimeter of a Circle using Radius:

Perimeter = 2πr

r is radius and Pi value is 3.14

Find the **Radius** of a **Circle** for a given **Perimeter**

Radius = square root (C / 2π)

C is Circumference or Perimeter and Pi value is 3.14

## Formula to Calculate Area and Perimeter of a Sector

Area of a Sector using Radius:

Area =(θ/360°) x πr²

r is radius, Pi value is 3.14 and 𝜃 is the angle of the sector.

Perimeter of a Sector using radius:

Perimeter = 2r + ((θ/360) × 2πr )

r is radius, Pi value is 3.14 and 𝜃 is the angle of the sector.

## Formula to Calculate Area and Perimeter of an Oval

**Area of Oval:**

Area = π(A + B)/2

A is Major Axis, B is Minor Axis and Pi value is 3.14

Perimeter of an Oval:

Perimeter = 2π square root((A² + B²)/2)

A is Major Axis, B is Minor Axis and Pi value is 3.14

## Formula to Calculate Area and Perimeter of an Ellipse

Area of Ellipse:

Area = πAB

A is Major Axis, B is Minor Axis and Pi value is 3.14

Perimeter of an Ellipse:

Perimeter = π (A + B) (1 + 3h / 10 +square root( 4 - 3h))

A is Major Axis, B is Minor Axis , h is (A - B)² / (A + B )² and Pi value is 3.14

## Formula to Calculate Area and Perimeter of a Rhombus

Area of a Rhombus:

Area = PQ / 2

P is Diagonal 1 and Q is Diagonal 2

Perimeter of a Rhombus:

Radius = 2 * square root (P² + Q²)/2

P is Diagonal 1 and Q is Diagonal 2

## Formula to Calculate Area and Perimeter of a Parallelogram

Area of Parallelogram:

Area = ( b*h)

h is height and b is base

Perimeter of Parallelogram

Perimeter = 2(a + b)

a and b are the length of two adjacent sides of parallelogram

## Formula to Calculate Area of a Square

Area of Square:

Area = a²

a is side

Find the Sides of a Square given its area

Side = Square Root (A)

A is area

Perimeter of Square:

Perimeter = 4a

a is side

Find Sides of a Square using Perimeter:

Side = P / 4

P is Perimeter

## Formula to Calculate Area and Perimeter of a Rectangle

Area of a Rectangle:

Area = L * W

L is Length and W is Width

Perimeter of Rectangle:

Perimeter = 2 * (L + W)

L is Length and W is Width

## Formula to Calculate Area and Perimeter of a Triangle

Area of Equilateral Triangle:

Area = square root (3)/4 a²

a is side

Area of Isosceles Triangle:

h = square root (a² - b²/4)

Area = bh

b is base and h is Height

Area of Scalene Triangle:

S = a + b + c / 2

Area = square root (s (s-a) (s-b) (s-c))

a, b and c are sides

Perimeter of Equilateral Triangle:

Perimeter = 3a

a is side

Perimeter of Isosceles Triangle:

Perimeter = 2a + b

b is base and a is side

Perimeter of Scalene Triangle:

Perimeter = a + b + c

a, b and c are sides

## Formula to Calculate Area and Perimeter of a Trapezoid

Area of Trapezoid:

Area = 1/2 (a + b) h

a and b are axes and h is height

Perimeter of Trapezoid:

Perimeter = (a + h + b + h)

a and b are axes and h is height

## Formula to Calculate Area and Perimeter of a Pentagon

Area of Pentagon:

Area = 1/4 square root(5 (5 + 2 square root(5)))a²

A is Side

Perimeter of Pentagon:

Perimeter = 5a

a is Side

## Formula to Calculate Area and Perimeter of a Hexagon

Area of Hexagon:

Area = 3 * square root (3) /2 a²

a is side

Perimeter of Hexagon:

Perimeter = 6a

a is side

## Formula to Calculate Area and Perimeter of an Octagon

Area of Octagon:

Area = 2(1 + square root (2))a²

a is Side

Perimeter of Octagon:

Perimeter = 8a

a is Side

## Formula to Calculate Area and Perimeter of a Kite

Area of Kite:

Area = ab/2

a is diagonal 1 and b is diagonal 2

Perimeter of Kite:

Perimeter = 2(a + b)

a is diagonal 1 and b is diagonal 2

## Frequently Asked Questions on Area Calculator

Area of a circle is πr² where r is radius and Pi value is 3.14

Area of a circle is πr² where r is radius and Pi value is 3.14