Question

Three circles are externally tangent to one another. The radius of each of the circles is 2 cm. A belt fits tightly around the three circles. Find the length of the belt. Express your answer in terms of pi with an explanation.

Answer 1

πd is the circumference of a circle, so with a diameter of 4 a single circle has a circumference of 4π. 1/3 of each circle is in contact with the belt, so that total part is still 4π. Then, the part of the belt connecting from tangent to tangent is 2 radii, so 3 areas is 12. The belt would then be 12+4π cm.

Answer 2

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3.
Which is greater, the circumference of a circle with radius 3 ft, or the distance around a semicircle with diameter 16 ft? By how much?
A. circle, by 4 ft
B. circle, by 2 ft
C. semicircle, by 4 ft
D. semicircle, by 2 ft