r=3.1

The area of a circle is equal to Pi π times the radius r squared.

π⋅(radius)2

Substitute in the value of the radius r=3.1 into the formula for the area of a circle. Pi π is approximately equal to 3.14.

π⋅3.12

Raise 3.1 to the power of 2.

π⋅9.61

Multiply π by 9.61.

30.1907054

Find the Area circle (3.1)