Question 115266
Area = (1/2)ab(Cos(C))
Find the area of the triangle ABC when c=12in, b=9in, angle A=60 degrees?
Area = (1/2)bc(Cos(A))
Area = (1/2)*9*12*Cos(60)
Area = 27 sq. in
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Find the area of the triangle ABC when three sides are a=9,b=12 and c=5 
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SSS Triangle Area Formula: the square root of (S(S - a)(S - b)(S - c)) where a, b, and c are sides and S is (a + b + c)/2
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S= (9+12+5)/2 = 13
Area = sqrt[13*(13-9)(13-12)(13-5)]
Area = sqrt[13*4*1*8]
Area = sqrt[416]
Area = 20.4 sq units
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Cheers,
Stan H.