Question 1111462
Use the law of cosines to get the length(l) of the third side
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l^2 = 77^2 + 76^2 - 2 * 77 * 76 * cos(47)
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l^2 = 3722.8912
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l = 61.0155
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use Heron's formula to calculate the area of the triangle
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s = (77 + 76 + 61.0155)/2 = 107.0078
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Area of triangle = square root(s * (s-a) * (s-b) * (s-c))
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Area of triangle = square root(107.0078 * (107.0078-77) * (107.0078-76) * (107.0078-61.0155)) = 2,139.9461 square feet
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Note that this solution works in all cases, the solution given by tutors that does not include the law of cosines fails when the included angle is > 90 degrees
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