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

#7**+8 **

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

#1**0 **

Good question. Do you know about the formula? Or may you give a hint?

DragonSlayer554
Jul 12, 2014

#6**+8 **

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

#7**+8 **

Best Answer

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