SOLUTION: The area of a circle is proportional to the square of its radius. If the area of a circle whose diameter is 5cm is 19.635 cm^2. What is the constant of proportionality? What is the

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Question 1173944: The area of a circle is proportional to the square of its radius. If the area of a circle whose diameter is 5cm is 19.635 cm^2. What is the constant of proportionality? What is the equation that describes the relation?
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Hi,
Area of a circle is proportional to the square of its radius
C = kR
19.635 = k 2.5^2
k = 19.635/6.25
k = 3.14
Area of Circle = 3.14 x R^2
Hope this helps :-)