Answer:
d = 2r or d = C/π
Diameter is equal to two times the radius or Circumference/π
C = 2πr
Circumference is equal to two times π multiplied the radius
A = π * r²
The area of the circle equals to π multiplied by the radius squared
Explanation:
Let's find the formulas for d, C and A
d = diameter
C = Circumference
A = Area
r = radius
π ≅ 3.1416
d = 2r or d = C/π
Diameter is equal to two times the radius or Circumference/π
C = 2πr
Circumference is equal to two times π multiplied the radius
A = π * r²
The area of the circle equals to π multiplied by the radius squared