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October 25, 2014

October 25, 2014

Posted by **aneesha** on Sunday, February 6, 2011 at 9:55am.

- math -
**dave**, Sunday, February 6, 2011 at 10:05amcheck out law of cosines

- math -
**helper**, Sunday, February 6, 2011 at 10:56amTriangle ABC

AB = x

BC = x - 4

AC = 10

angle BAC = 60 deg

Using Law of Cosines

a^2 = b^2 + c^2 - 2bc cos A

(x -4)^2 = 10^2 + x^2 - 2(10)(x)cos 60

x^2 - 8x + 16 = 100 + x^2 - 20x (0.5)

x^2 - 8x + 16 = 100 + x^2 - 10x

2x = 84

x = 42

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