Radian Question

  • Thread starter Miike012
  • Start date
  • #1
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Homework Statement


Just got done reading the chapter... Want to make sure I have this right....

IF Circumference = 2(pi)r
Let cir = 360 deg.
So that 360 deg = 2(pi)r

And 180 deg = (pi)r

IF r = 10
then 180 = (pi)10

Hence half of a cirlce with radius of 10 has an arc measure of 10(pi).....

Is this correct?


And if I wanted to find An arc measure of angle 70 deg I would
solve for x
180x = 70
x = 70/180 = 7/18
then
70 = (7/18)(Pi)(10)
If radius is 10....

Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
rock.freak667
Homework Helper
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360° ≡ 2π

In your working you equated 360 to 2πr meaning that you equated degrees to a length, which is incorrect.
 
  • #3
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isnt the equation for circumference 2(pi)r?
and circumference refers to the entire circle which is 360 deg.
 
  • #4
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Well.....
 
  • #5
rock.freak667
Homework Helper
6,230
31
isnt the equation for circumference 2(pi)r?
and circumference refers to the entire circle which is 360 deg.

360 degrees would be the ratio of the circumference of the circle to its diameter.
 
  • #6
196
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that's exactly right except that the arc length should be (7pi/18)(10) not (7/18)pi
 

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