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# a challenge question for anyone to try and answer

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The circumference of a circle is 78.12 cm. A student was asked to approximate the area of the circle.

incorrectly said the area of the circle is about 972 cm squared. What is the approximate area of the​ circle? Use 3.14 for pi What mistake might the student have​ made?

​(Round the final answer to the nearest whole number as needed. Round all intermediate values to the nearest thousandth as​ needed.)

Mooieplier  Feb 28, 2017
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I would approximate the radius as ≈ 13 cm

So....the estimated area = pi * (13)^2  =  169 pi   ≈  170 * 3   ≈  510 cm^3

The true area  is  pi *(78.12/ [2pi])^2  ≈ 486 cm^2

[ Don't see what error the student might have made ]

CPhill  Feb 28, 2017
#4
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The formula for circumference is 2πr

The formula for area of a circle is 2 times pi times radius squared

I really hope that this helps you. Keep trying. Math IS hard!

Guest Feb 28, 2017

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