Question 1085091: Another question from my CCT part 2 that i did not understand at all.
Three people are standing apart from each other in the frm of a triangle. Fred is 5cm away from Angela 6cm away from Mark and Mark is 7cm away from fred. What angles do they make.
Answer by addingup(3677)   (Show Source):
You can put this solution on YOUR website! our sides are a, b, and c
our angles are A, B, and C
a = 5
b = 6
c = 7
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cos C = (a^2+b^2-c^2)/(2ab)
cos C = (5^2+6^2-7^2)/(2*5*6) = 0.2
C = cos^-1(0.2) = 78.46 degrees
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cos A = b^2+c^2-a^2)/(2bc)
cos A = (6^2+7^2-5^2)/(2*6*7) = 0.714
A = cos^-1(0.74) = 42.27 degrees
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to find our third angle, let's remember that the sum of the angles of EVERY triangle equal 180 degrees:
180-(78.46+42.27) = 59.27 degrees
So there you have it, those are your three angles.
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