# Math Q:

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When the book ask for exact value..doesn't that mean to work the problem out completely?

Ex.

Find the circumference of a circle that has a diameter of 1.5 in. Give the exact value.

Ds said

C=pi(d)

C=pi(1.5)

C=4.71in

The book says

C=pi(d)

C=pi(1.5)

C=1.5pi in.

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The book answers with pi because multiplying by 3.14 for pi is actually rounding pi, making the answer less exact.

I've been working on English papers all morning (so my brain is mush because this is so not my strength), so I can't remember the exact term, but pi is irrational wich means it cannot be written as a neat fraction or a terminating decimal. To answer with anything but a pi in the answer is rounding the answer.

Hope that helps.

Linda

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When the book ask for exact value..doesn't that mean to work the problem out completely?

Ex.

Find the circumference of a circle that has a diameter of 1.5 in. Give the exact value.

Ds said

C=pi(d)

C=pi(1.5)

C=4.71in

The book says

C=pi(d)

C=pi(1.5)

C=1.5pi in.

Since pi is an irrational number , it cannot be written as the ratio of two integers, so when pi is written as a decimal it does not repeat, nor terminate.

Therefore, the closest we can get to the answer is an approximation; so the exact answer would be written as pi*diameter. (1.5 pi)

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