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Math Help - Isosceles triangle

  1. #1
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    Isosceles triangle

    How do I find the are of an isosceles triangle with two sides length 4 and the inbetween angle is theta? I know the answer is 8 sin theta.
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  2. #2
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    Quote Originally Posted by Stuck Man View Post
    How do I find the are of an isosceles triangle with two sides length 4 and the inbetween angle is theta? I know the answer is 8 sin theta.
    Angle C = \theta

    Since side c is opposite angle C it means that A = B = 4

    The area of a circle is given by \frac{1}{2}ab \sin \theta
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  3. #3
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    Yes I should have known that. Questions usually have different letters to the common rules. Do you recommend writing the rules with the usual letters a, b and c and then converting to the questions letters?
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  4. #4
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    Quote Originally Posted by Stuck Man View Post
    Yes I should have known that. Questions usually have different letters to the common rules. Do you recommend writing the rules with the usual letters a, b and c and then converting to the questions letters?
    Do what works best.

    \frac{1}{2}ab \sin (C) = \frac{1}{2}ac \sin(B) = \frac{1}{2}bc \sin(A)

    My favoured method is to change the symbols in the question to match the first expression
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