how to calculate area of circle?

a = πr^2
(area = pi * radius * radius)

If you have the radius of the circle it is A=Pi*r^2 where Pi≈3.141592654, if you are given it as a function (ie y=+-sqrt(1-x²)) then you would be best of getting the standard form of the equation of the circle (which in this case would be X^2+Y^2=1 where then r would be sqrt(1) = 1, so you would get A=Pi*r^2 = Pi.

Cool just PIE R^2 or PIE D where r=radius an D =diameter of the circle.

area of circle = pi*(radius^2)


pi= 3.14 or 22/7 as per given

formula to find the area of the circle is pi* r^2.
where pi = 22/7 or 3.14
r is the radius of the circle

area of a circle = pi * radius^2 , pi = 3,14159

simple my friend pi*r^2 so if you had a circle with a diameter of 4cm, you half it to find the radius (2cm) then you would do 2Cm^2*pi for this it would be roughly (from my head) 12cm.

Area = pi * (radius)^2

area of a circle = pi * radius^2 , pi = 3,14

area of a circle is = pi*(radius)^2
pi=3.1412
for eg:a circle of radius 2cm is give .calculate the are of circle?
formula: Area of circle is 2*pi*r^2
2*3.1412*(2)^2
2*3.1412*4
25.1296 sq cms