Arc

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Oct 28th 2012, 01:32 PM
M670

Arc

The radius of the circle with a central angle of http://webwork.mathstat.concordia.ca...219fe87b11.png that intercepts an arc with length 9 miles is miles.

I came up with 2.02 miles
or 12.7 miles both seem wrong
but then if the formula is S=r(theta) and I would get 9=r(255) r=9/255 r=.035?
I am just not sure what to do?
Oct 28th 2012, 01:38 PM
skeeter

Re: Arc

$s = r\theta$ is only valid if $\theta$ is in radians
Oct 28th 2012, 01:42 PM
M670

Re: Arc

can't I convert it by multiplying (pi/180)
So it would be 255(pi/180)= 4.45 radians
Oct 28th 2012, 01:44 PM
skeeter

Re: Arc

yes
Oct 28th 2012, 01:45 PM
M670

Re: Arc

which would then be 9/4.45=2.02 miles as my radius
Oct 28th 2012, 02:08 PM
skeeter

Re: Arc

Quote:

Originally Posted by M670

which would then be 9/4.45=2.02 miles as my radius

"seem wrong" now?
Oct 28th 2012, 05:53 PM
M670

Re: Arc

Quote:

Originally Posted by skeeter

"seem wrong" now?

I really can't see my mistake... in this question
The process looks good to me, I convert 255 degrees into radians then use the formula to derive 2.02 miles as my radius
Oct 28th 2012, 06:11 PM
Plato

Re: Arc

Quote:

Originally Posted by M670

I really can't see my mistake... in this question
The process looks good to me, I convert 255 degrees into radians then use the formula to derive 2.02 miles as my radius

I think people who still use degrees, get what they deserve.
Let $\theta=255\cdot\frac{\pi}{180}$ then $r=\frac{9}{\theta}$ .
You should get $2.02220398281467$ .

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