Respuesta :

Diameter: 40 inches
Area: 3.14*20*20
Circumprince: 3.14*40
diameter=radius times 2
circumference=diameter times pi
area=pi times radius^2


so
given
radius=20 inches
diameter=20 times 2=40 inches
circumference 40 times pi=40pi inches
area=pi times 20^2=pi times 400=400pi square inches