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# Whats the linear measure of an arc whose central angle is 80* on a circle having a radius of 18 meters?

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Whats the linear measure of an arc whose central angle is 80* on a circle having a radius of 18 meters?

Rose98  Jul 12, 2014

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I really liked this question Rose.

I'd do it CPhill's way.

the whole circumference it 2pi*r

But you only have 80degrees out of a total of 360 degrees in the whole cirlce.

so the answer must be given by

$$arc\;length= \frac{80}{360}\times 2\pi r => \frac{80}{360}\times 2\pi\times 18$$    etc

Melody  Jul 12, 2014
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Good question. Do you know about the formula? Or may you give a hint?

DragonSlayer554  Jul 12, 2014
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arc length/circumference=degree measure/360*

Rose98  Jul 12, 2014
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Okay. I'll try.

DragonSlayer554  Jul 12, 2014
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First, what is circumference, and what is arc length?

DragonSlayer554  Jul 12, 2014
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Rose98  Jul 12, 2014
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The total circumference is 2*pi*18  = 36pi

Note that we only want (80/360)ths = (2/9)ths of this.

So, (80/360)*36pi  = (2/9)*36pi = 8pi

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The above is a "corrected" answer!!...Mainly because I forgot what I was doing!!!

CPhill  Jul 12, 2014
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+93677
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I really liked this question Rose.

I'd do it CPhill's way.

the whole circumference it 2pi*r

But you only have 80degrees out of a total of 360 degrees in the whole cirlce.

so the answer must be given by

$$arc\;length= \frac{80}{360}\times 2\pi r => \frac{80}{360}\times 2\pi\times 18$$    etc

Melody  Jul 12, 2014
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Thank you guys:) I am really getting this whole Geometry thing now! :D

Rose98  Jul 12, 2014
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Geometry is fun when you get the hang of it!

Melody  Jul 12, 2014
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Never thought it would be, but now I am seeing the fun part :)

Rose98  Jul 12, 2014
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I wish i too could see the fun part of Geometry like u Rose!

But im happy u saw it!lol!

rosala  Jul 13, 2014