Circle circumference and radius worksheet for math practice.

To solve these problems, we need to find the Circumference ($C$), Radius ($r$), and Diameter ($d$) for each circle based on the information given in the diagram.

Here are the formulas we will use:
* Diameter ($d$): The distance across the circle passing through the center. It is twice the radius ($d = 2 \times r$).
* Radius ($r$): The distance from the center to the edge. It is half the diameter ($r = d / 2$).
* Circumference ($C$): The distance around the circle. We can calculate this using $C = \pi \times d$ or $C = 2 \times \pi \times r$. (We will use $\pi \approx 3.14$).

Let's go through each problem step-by-step.

Problem 1:
* Given: The line goes all the way across the center, labeled "10 in." This is the Diameter ($d$).
* $d = 10 \text{ in}$
* Find Radius ($r$): Divide the diameter by 2.
* $r = 10 / 2 = 5 \text{ in}$
* Find Circumference ($C$): Multiply the diameter by $\pi$ ($3.14$).
* $C = 3.14 \times 10 = 31.4 \text{ in}$

Problem 2:
* Given: The line goes all the way across the center, labeled "30 cm". This is the Diameter ($d$).
* $d = 30 \text{ cm}$
* Find Radius ($r$): Divide the diameter by 2.
* $r = 30 / 2 = 15 \text{ cm}$
* Find Circumference ($C$): Multiply the diameter by $\pi$ ($3.14$).
* $C = 3.14 \times 30 = 94.2 \text{ cm}$

Problem 3:
* Given: The line goes from the center to the edge, labeled "1.75 m". This is the Radius ($r$).
* $r = 1.75 \text{ m}$
* Find Diameter ($d$): Multiply the radius by 2.
* $d = 1.75 \times 2 = 3.5 \text{ m}$
* Find Circumference ($C$): Multiply the diameter by $\pi$ ($3.14$).
* $C = 3.14 \times 3.5 = 10.99 \text{ m}$

Problem 4:
* Given: The line goes from the center to the edge, labeled "4 m". This is the Radius ($r$).
* $r = 4 \text{ m}$
* Find Diameter ($d$): Multiply the radius by 2.
* $d = 4 \times 2 = 8 \text{ m}$
* Find Circumference ($C$): Multiply the diameter by $\pi$ ($3.14$).
* $C = 3.14 \times 8 = 25.12 \text{ m}$

Problem 5:
* Given: The line goes all the way across the center, labeled "100 mi". This is the Diameter ($d$).
* $d = 100 \text{ mi}$
* Find Radius ($r$): Divide the diameter by 2.
* $r = 100 / 2 = 50 \text{ mi}$
* Find Circumference ($C$): Multiply the diameter by $\pi$ ($3.14$).
* $C = 3.14 \times 100 = 314 \text{ mi}$

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Final Answer:
1. C = 31.4 in, r = 5 in, d = 10 in
2. C = 94.2 cm, r = 15 cm, d = 30 cm
3. C = 10.99 m, r = 1.75 m, d = 3.5 m
4. C = 25.12 m, r = 4 m, d = 8 m
5. C = 314 mi, r = 50 mi, d = 100 mi