equation for working out circumference and area of a cricle?

1] area of circumference is= 2 * pi * r,( r is radius of circle)

2]area of circle = pi * r * r

c = 2πr
(circumference = 2 * pi * radius)

a = πr^2
(area = pi * radius * radius)

pi x radius^2 is the equation for area
pi x diameter is the equation for the circumference (diameter= radius x 2 if only radius is given)

c=2pir
a=pir^2

radius is r
C = 2 π r
A = π r ²