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We are going over sine, cosine and tangent, but most recently law of cosine. How do you find the area of a non right triangle using law of cosine?
 Feb 7, 2012

You dont find it with the law of cosine....



you use the law of cosine to find the length of the triangle's edge. if you want to find the triangle's area you need to use the law:


 Mar 26, 2017

It depends upon what we know about the triangle......


If we know two sides and an included angle between these sides, then Erlich's approach is correct.


If we only know the three sides, we can use someting known as "Heron's Formula"  which is


Area  = sqrt [ s * (s - a) * (s - b) * (s - c) ]


Where a, b, c are the sides and "s"  is the semi-perimeter given by

[ a + b + c ] / 2





cool cool cool

 Mar 26, 2017

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