Circle diameter = 9
Answer
r = 4.5
C = 9π or 28.2743
A = 20.25π or 63.6173
↓Steps Explained:↓

A circle has diameter = 9
Calculate Area, Circumference, Radius, Diameter
Calculate radius (r):
d = 2r
Rearranging the equation, we get:
r = 4.5
Calculate circumference (C):
C = 2πr
C = 2π * 4.5
C = 9π or 28.2743
Calculate Area (A):
A = πr2
A = π * 4.52
A = 20.25π or 63.6173
Final Answers
r =
4.5C =
9π or
28.2743A =
20.25π or
63.6173Related Calculators:
Unit Circle |
Circle Equation |
Annulus