Geometry

Area of a circle calculator

Area of a circle calculator - calculating area of a circle online. Area of a circle - is a numerical characteristic that characterizes the size of a plane bounded by a circle line. Area of a circle can be calculated using the number pi and the radius of the circle, or using other known input data. Our calculator will help you to calculate the area of a circle for free online or to check the already performed calculations.


Table with circle area formulas (at the end of the page)




1

Circle Area Through Radius

Circle Area Through Radius
... preparation ...
r - radius


2

Circle area through diameter

Circle area through diameter
... preparation ...
D - diameter


3

Area of a circle along the circumference

Area of a circle along the circumference
... preparation ...
- circumference


4

Area of a circle through a square inscribed in a circle

Area of a circle through a square inscribed in a circle
... preparation ...
a - side


5

Area of the circle inscribed in a square

Area of the circle inscribed in a square
... preparation ...
A - side


6

Area of the circle described around an arbitrary triangle

Area of the circle described around an arbitrary triangle

This formula is applicable only if a circle can be described around a triangle, that is, all three vertices of the triangle must lie on the line of the circle. The triangle in this case can be any.

To calculate the area of a circle, first calculate the semi-perimeter of a triangle  

... preparation ...

a - side
b - side
c - side


7

Area of a circle described near an equilateral triangle

Area of a circle described near an equilateral triangle
... preparation ...
a - side


8

Area of a circle described around an equilateral triangle, calculated from the height of the triangle

Area of a circle described around an equilateral triangle, calculated from the height of the triangle
... preparation ...
h - height


9

Area of a circle about an isosceles triangle

Area of a circle about an isosceles triangle
... preparation ...
a - side
b - base


10

Area of the circle described about a right triangle

Area of the circle described about a right triangle
... preparation ...
a - side
b - side


11

Area of a circle inscribed in an isosceles triangle

Area of a circle inscribed in an isosceles triangle
... preparation ...
a - side
b - base


12

Area of a circle inscribed in an isosceles triangle, calculated on the sides of the triangle and the angle between them

Area of a circle inscribed in an isosceles triangle, calculated on the sides of the triangle and the angle between them
... preparation ...
b - side
α - angle between parties


13

Area of a circle inscribed in a right triangle

Area of a circle inscribed in a right triangle
... preparation ...
a - side
b - side
c - side


14

Area of a circle inscribed in a right triangle, calculated by the side and angle

Area of a circle inscribed in a right triangle, calculated by the side and angle
... preparation ...
b - side
α - angle at base


15

Area of a circle inscribed in an equilateral triangle

Area of a circle inscribed in an equilateral triangle
... preparation ...
a - side


16

Area of a circle inscribed in an isosceles trapezium, calculated from the base of the trapezium and the angle at the base

Area of a circle inscribed in an isosceles trapezium, calculated from the base of the trapezium and the angle at the base
... preparation ...
b - side
α - angle at base


17

Area of a circle described near an isosceles trapezium, calculated along the sides of the trapezium, its diagonal and base

Area of a circle described near an isosceles trapezium, calculated along the sides of the trapezium, its diagonal and base

To calculate the area of a circle, first calculate the semi-perimeter of a triangle ABC   

... preparation ...

a - side
c - side
d - diagonal


18

Area of the circle described near the rectangle

Area of the circle described near the rectangle
... preparation ...
a - side
b - side


19

Area of a circle described near a regular polygon

Area of a circle described near a regular polygon
... preparation ...
a - side
N - the number of sides of the polygon


20

Area of a circle described about a regular hexagon

Area of a circle described about a regular hexagon
... preparation ...
a - side

Note:

If the angle is specified in radians in the source data, then for conversion to degrees you can use the formula: 1 radian × (180/π)° = 57,296°


Table with circle area formulas


initial data
(active link to go to the calculator)
sketch formula
1 radius
2 diameter
3 circumference
4 side of a square
5 side of a square
6 side of the triangle
where 
7 side of an equilateral triangle
8 equilateral triangle height
9 side and base
10 side at right angle of triangle
11 side and base
12 sides and angle between them
13 side of a right triangle
14 side and angle at the base of the triangle
15 side of an equilateral triangle
16 side and angle at the base of the trapezoid
17 sides and diagonal of the trapezoid
where 
18 side of the rectangle
19 side and number of sides of the polygon
20 hexagon side


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