Question

If the circumference of the circle below is 42 cm, what is the length of arc AB?

Answer 1

if the arc was 360 degrees, then it would make up the entire circle and it would be 42 cm (since that's the circumference)

however, it's not 360 degrees and it's actually 120 degrees

so how can we use this to find the arc length?

Answer 2

OH, you divide 42 by 3, since 120 degrees is 1/3 of the circle.

Answer 3

yep, you're multiplying the overall circumference by 1/3 since 120 degrees is 1/3rd of a full 360 degree circle

Answer 4

you nailed it

Answer 5

So the answer is 14?

Answer 6

correct

Answer 7

in general, the formula is

Answer 8

s = (angle/360)*Circumference

that turns into

s = (angle/360)*2*pi*r

or

s = (angle/360)*pi*d


s = arc length
r = radius
d = diameter

Answer 9

Thank you very much!

Answer 10

yw