Results 1 to 3 of 3

Math Help - given area of triangle determine value of sin C.

  1. #1
    Banned
    Joined
    Jul 2008
    Posts
    19

    given area of triangle determine value of sin C.

    Triangle ABC has an area of 18cm^2. If a=5 and b=12, What does sin C equal?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Jul 2008
    Posts
    21
    I think this wants you to use the rule 1/2absinC = A, in words "the area of a triangle = 1/2 the product of two sides multipied be the sine of the angle between them so in you case 1/2 x 12 x 5sinC = 18
    30sinC = 18
    sinC = 3/5
    C = 36.86989765 degrees


    Hope that helps!
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member Jonboy's Avatar
    Joined
    May 2007
    From
    South Point
    Posts
    193
    I approached this problem differently. Here's my famous picture:


    We know the area.

    So we can derive: \frac{12\cdot h}{2} = 18

    Simplify: 12h = 36\rightarrow h = 3

    So Sin\,C = \frac{3}{5}

    And for the angle measure: Sin^{-1}\big(\frac{3}{5}\big) \approx 37^o

    I'm glad me and gtbiyb agree!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Determine if this is a right triangle.
    Posted in the Calculus Forum
    Replies: 7
    Last Post: June 6th 2010, 02:55 PM
  2. Replies: 9
    Last Post: March 14th 2010, 08:46 AM
  3. Replies: 1
    Last Post: October 28th 2008, 07:02 PM
  4. Replies: 7
    Last Post: July 19th 2008, 06:53 AM
  5. Replies: 27
    Last Post: April 27th 2008, 10:36 AM

Search Tags


/mathhelpforum @mathhelpforum