Question

Find the area of a circle with a circumference of 31.4 units

Answer 1

78.5 unit^2

_____________________

A=pir^2

A= pi*5^2

A=25 pi

A= 78. Unit^2

Answer 2

the area of the circle is pi*(5 units)^2 = 25*pi units^2

Explanation:

The formula for the circumference of a circle is C = 2*pi*r, where r is the radius. Then the formula for the radius, r, is r = C/(2*pi).

Here the circumference is C = 31.4 units, so the radius is

31.4 units

r = -------------------

6.28

or r = 5 units.

The area of the same circle is A = pi*r^2.

Here, with r = 5 units, the area of the circle is pi*(5 units)^2 = 25*pi units^2.