Results 1 to 3 of 3

Math Help - Radian Measure

  1. #1
    Junior Member
    Joined
    Jun 2007
    Posts
    52

    Radian Measure

    5 a. Determine the measure of the central angle that is formed by an arc length of 5 cm in a circle with a radius of 2.5cm. Express the measure in both radians and degrees correct to one decimal place.

    5cm
    2.5 radius

    so 2 radians?

    that's all i can think of i dont really know how to approach this problem i was away for a couple of days from school.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,605
    Thanks
    1573
    Awards
    1
    Quote Originally Posted by Skoz View Post
    5 a. Determine the measure of the central angle that is formed by an arc length of 5 cm in a circle with a radius of 2.5cm. Express the measure in both radians and degrees correct to one decimal place.

    \frac{5}{2.5} so 2 radians?
    That is exactly right.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member pflo's Avatar
    Joined
    Apr 2009
    From
    Albuquerque, NM
    Posts
    155
    Thanks
    7
    Think of arc-length as part-way around a circle. If you go 20% of the way around a circle, you've gone 20% of the diameter. You've also subtended 20% of the 360 degrees in the circle.

    Your circle has a circumference of C=2{\pi}*r=2{\pi}*2.5=5{\pi}

    Remember percents are always calculated using {{part}/{whole}} (times 100). If you've gone 5 cm around the circle, then you've gone {5}/{5\pi}=1/{\pi} of the circle, or {1}/{\pi} of 360 degrees, or {1}/{\pi} of 2{\pi} radians.

    Half of the way around would be 2{\pi}*1/2 radians and one-fifth of the way around would be 2{\pi}*1/5 radians. For {1}/{\pi} of the way around, the answer is 2{\pi}*{1}/{\pi}=2radians.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Radian Measure
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: July 17th 2011, 05:30 PM
  2. Radian measure
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: November 24th 2009, 03:59 PM
  3. Radian Measure
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: November 24th 2009, 03:10 AM
  4. Radian Measure?
    Posted in the Algebra Forum
    Replies: 1
    Last Post: May 9th 2009, 09:34 AM
  5. Radian Measure 2
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: December 22nd 2008, 11:38 PM

Search Tags


/mathhelpforum @mathhelpforum