LittleCalc.com
Areas
Areas
Area of a square
Area of a rectangle
Area of a triangle
Area of a circle
Area of a rhombus
Area of a trapezoid
Area of a parallelogram
Volumes
Volumes
Volume of a cube
Volume of a cylinder
Perimeters
Perimeters
Perimeter of a square
Perimeter of a rectangle
Perimeter of a triangle
Perimeter of a circle
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Area of a circle
Area A = π x r²
with π (number pi) approximately equal to 3.14
Radius = AO = OB = r
Diameter = AB = 2 r
Example
Take a circle with radius r = 5 cm
Area A of the circle = π x r² ≈ 3.14 x 5² ≈ 78.5 cm²
Calculate the area of a circle
Radius
Area of the circle