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Leviafan [203]
3 years ago
12

The area of a circle varies directly with the square of its radius.if the area 4πcm² when the radius is 2cm, find the area when

the radius is 3cm
Mathematics
1 answer:
goldenfox [79]3 years ago
5 0

Answer:

A = 9π cm²

Step-by-step explanation:

Given that area (A) varies directly with r² then the equation relating them is

A = kr² ← k is the constant of variation

To find k use the condition A = 4π when r = 2 , then

4π = k × 2² = 4k ( divide both sides by 4 )

π = k

A = πr² ← equation

when r = 3 , then

A = π × 3² = 9π cm²

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