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Geometry 10 Online
OpenStudy (anonymous):

Can someone please help me with finding the measure of a central angle of a circle please?? Also finding the arc length between two points. Im completely lost.

OpenStudy (amistre64):

can you provide an example?

OpenStudy (anonymous):

Well I have to find the central angle of a ferris wheel that has a diameter of 150 meters

OpenStudy (anonymous):

I also have to find the arc length between each car of the ferris wheel, there are 28 cars

OpenStudy (amistre64):

28 cars, divides a full circle into how many arcs?

OpenStudy (anonymous):

If I can find the answer to one of those questions I can get the other one by myself lol

OpenStudy (anonymous):

ummm it divides it into 28 arcs, correct?

OpenStudy (amistre64):

right so,360 degrees is a full circle, divided into 28 arcs ... what is 1/28th of 360?

OpenStudy (anonymous):

about 12.86

OpenStudy (amistre64):

so the angle from car to car is about 12.86

OpenStudy (amistre64):

degrees

OpenStudy (amistre64):

the arc length is just 1/28th of the circumference ... how do we determine the circumference of a circle?

OpenStudy (anonymous):

ohhhhh okay, let me figure out the central angle and see if I get the correct answer :)

OpenStudy (anonymous):

the circumference is 471.24

OpenStudy (anonymous):

because 2pi(75) = 471.2389

OpenStudy (amistre64):

2(75) = 150 ... d*pi is another way to express 2pi r

OpenStudy (amistre64):

so yeah 150pi/28 should be the arc length

OpenStudy (anonymous):

that gives me 16.83

OpenStudy (amistre64):

yep

OpenStudy (amistre64):

keep in mind that for the central angle, if they want radians ... that would be 2pi/28

OpenStudy (anonymous):

So, i thought I would be able to find the central angle measure on my own but I was wrong lol. How would I be able to find the central angle measure with the arc length?

OpenStudy (anonymous):

And thank you so much for helping me

OpenStudy (amistre64):

well... 2pi r/28 is arclength and 2pi/28 is that radian angle ... 2pi r/28r arclength divided by r gives radian measure of angle

OpenStudy (amistre64):

good lcuk

OpenStudy (anonymous):

I got .2244

OpenStudy (anonymous):

So would I move the decimal over 2 places?

OpenStudy (amistre64):

.2244 radians is correct, no need to move anything

OpenStudy (anonymous):

oh.. okay, soooooo my central angle measure is .23 and my arc length is 16.83? :)

OpenStudy (amistre64):

seems fair to me

OpenStudy (amistre64):

or 360 degrees/28 gives us the degree of the angle instead of the radian

OpenStudy (anonymous):

Thank you so much! You're a life saver!

OpenStudy (amistre64):

yw

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