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Homework Help: Area of triangle

  1. Jan 29, 2010 #1
    1. The problem statement, all variables and given/known data
    Show that the area of a triangle with sides of lengths a and b with included angle theta is...

    A = 1/2 a*b*sin(theta)

    I am not sure what this question is really asking. Any help?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jan 29, 2010 #2
    i believe strongly that you can figure it out.
  4. Jan 29, 2010 #3
    If the area of a triangle is 1/2 b*h, and sin theta = opp/hyp, then that means a=h and b=b. Correct? Now how do I prove that the area is 1/2 a*b*sin(theta). I drew a right triangle and labeled the sides a and b, and the angle theta.
  5. Jan 29, 2010 #4
    It isn't necessarily a right triangle. Try making side "a" the base and dropping a height "h" down from the opposite corner.
  6. Jan 29, 2010 #5


    Staff: Mentor

    Furthermore, since the OP's problem states only that it is a triangle, he/she should not assume that it is a right triangle.
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