The radius of the circular lens of a magnifying glass is 4 centimeters what is the area in square centimeters of the glass

The area of a circle is:

A=πr^2, where π is the constant pi and r is the radius of the circle.

In this case the radius is 4cm:

A=π (4^2) cm^2

A=16π cm^2 (exact)

A≈50.27 cm^2 (to the nearest hundredth of a square centimeter)