Answer:
396 cm
Explanation:
You want the distance traveled by a wheel of radius 21 cm in 3 revolutions.
Circumference
The circumference of the wheel is ...
C = 2πr
C = 2π(21 cm) = 42π cm
Revolutions
In 3 revolutions of the wheel, it travels 3 times that distance, or ...
3(42π cm) = 126π cm ≈ 396 cm
The distance traveled is about 396 cm.
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Additional comment
The value shown is rounded to the nearest centimeter. The attachment shows the value to higher precision, for the usual approximations of pi.
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