Results 1 to 2 of 2

Math Help - triangles

  1. #1
    Newbie
    Joined
    Jul 2007
    Posts
    11

    triangles

    just a few questions: what is the cosine rule? and the sine rule? any formulas? thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    10,211
    Thanks
    419
    Awards
    1
    Quote Originally Posted by miley_22 View Post
    just a few questions: what is the cosine rule? and the sine rule? any formulas? thanks!
    Given a triangle with sides a, b, and c, and angles opposite those sides A, B, and C respectively:
    This is the Law of Sines:
    \frac{a}{sin(A)} = \frac{b}{sin(B)} = \frac{c}{sin(C)}

    These are the Law of Cosines:
    a^2 = b^2 + c^2 - 2bc~cos(A)

    b^2 = a^2 + c^2 - 2ac~cos(B)

    c^2 = a^2 + b^2 - 2ab~cos(C)
    (The Law of Cosines may be thought of as a generalization of the Pythagorean Theorem to triangles not necessarily including a right angle.)

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: March 19th 2011, 05:42 AM
  2. Triangles
    Posted in the Geometry Forum
    Replies: 2
    Last Post: March 8th 2011, 11:37 AM
  3. Triangles
    Posted in the Geometry Forum
    Replies: 1
    Last Post: April 12th 2009, 06:59 AM
  4. triangles
    Posted in the Geometry Forum
    Replies: 1
    Last Post: March 24th 2009, 08:06 AM
  5. How Many Different Triangles?
    Posted in the Geometry Forum
    Replies: 0
    Last Post: October 16th 2008, 07:29 PM

Search Tags


/mathhelpforum @mathhelpforum