I think you mean circumference...Area is 
. We have the area so we need to use it to solve for the radius which we will then use in the circumference formula. 
. Divide both sides by pi to get 
. Of course the simplification of the left side gives us 
and r = 4. Now fill that in to the circumference formula, which is 
, to get C
which is a circumference of 
The diameter of a circle is 15 ft. Find its circumference in terms
2 answers:
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Find the rate in which both balls make one full rotation around the track.
Ball A:
It takes 30 seconds for Ball A to make a full rotation.
Ball B:
It takes 20 seconds for Ball B to make a full rotation.
Find the least common multiple of 20 and 30 to find the time at which they'll meet.
Multiples of 20: {20,40,60}
Multiples of 30: {30,60}
60 is the least common multiple of both 20 and 30.
The balls will meet again at 60 seconds.
Ball A:
It takes 30 seconds for Ball A to make a full rotation.
Ball B:
It takes 20 seconds for Ball B to make a full rotation.
Find the least common multiple of 20 and 30 to find the time at which they'll meet.
Multiples of 20: {20,40,60}
Multiples of 30: {30,60}
60 is the least common multiple of both 20 and 30.
The balls will meet again at 60 seconds.