SOLUTION: How do you find the area of a triangle if two sides are 4 inches and 5 inches and the included angle is 120 degrees?

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Question 253199: How do you find the area of a triangle if two sides are 4 inches and 5 inches and the included angle is 120 degrees?
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
The formula you need here is
(i) A+=+%281%2F2%29%2Aab%2Asin%28C%29
where a and b are the sides and C is the "included" angle.
From (i) we have
A+=+%281%2F2%29%2A%284%29%2A%285%29%2Asin%28120%29
sin(120) = sqrt(3) / 2
A+=+%281%2F2%29%2A20%2Asqrt%283%29%2F2
A+=+5%2Asqrt%283%29