Question

Im sorry for so many questions but i need help badly.

Answer 1

The ratio of the circumference to the diameter is defined as pi
pi=circumference/diameter
that is how they got pi
in this question it woul be 15.7/5 which would be 3.14,





c=2pir
a=pir^2

c=2pir=16pi
divide both sides by 2pi
r=8

a=pir^2
a=pi8^2
a=pi64
a=64pi in²