Question

Please find the area and circumference of the circle with diameter 3.7cm

Answer 1

Answer:

Area: 10.7521 cm

Circumference: 11.62389 cm

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Solve: Area

Area, A, will equal the formula of $\pi r^2$, so we must find the value and split that up. Diameter, d is equal to 2r. Let's solve.

$A = \pi r^2$

$d = 2r$

Now, make an equation combining like terms.

$A = \frac{1}{4} \pi d^2$

This equation means to multiply those terms together. Since the diameter is 3.7, d is 3.7

$\frac{1}{4} * \pi * 3.7 = 10.8(estimate)~cm$

Let's move on to circumference. On we go!

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Solve: Circumference

With circumference, it is very similar to what you just did to find area(A). You must again, set up these terms and make an equation out of them. C(circumference) is going to be equal to $\pi r$, notice how it does not say squared($^2$) at the end now.

$C = \pi r$

And diameter, you guessed it, will be 2r.

$d = 2r$

Now, combine the like terms into an equation.

$C = \pi d$ pi times diameter(3.7)

$\pi * d(3.7) = 11.6~cm$

Now that the problem is done, we move on to review.

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What have we learned?

We learned how to solve for circumference and area using diameter.

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Questions?

Feel free to ask in the comments.