Find the one of a circle making use of the formulas: (C = pi d); (C = 2pi r).

You are watching: Find the circumference. leave your answer in terms of

**Circumference** is the distance about a **circle**. The circumference can additionally be dubbed the perimeter that a circle. However, we usage the ax circumference because that circles due to the fact that they are round.

**Circumference Formula:** (C=pi d) where the **diameter** (d=2r), or double the **radius**. For this reason (C=2pi r) together well.

Example (PageIndex5)

The tires top top a compact car are 18 customs in diameter. How far does the vehicle travel after the tires rotate once? How far does the auto travel after 2500 rotations of the tires?

Figure (PageIndex3)**Solution**

One turn of the tires is the circumference. This would certainly be (C=18pi approx 56.55 ext in. ) 2500 rotations would be (2500cdot 56.55) in approx 141,375 in, 11,781 ft, or 2.23 miles.

## Review

Fill in the following table. Leave all answers in terms of (pi).

*diameter*

*radius*

*circumference*1. | 15 | ||

2. | 4 | ||

3. | 6 | ||

4. | (84pi) | ||

5. | 9 | ||

6. | (25pi) | ||

7. | (2pi) | ||

8. | 36 |

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Square (PQSR) is inscribed in (igodot T). (RS=8sqrt2).