Question 1042353
Solve the triangle ABC. (using the law of cosines)

a=10,b=12,c=16
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You should do that.
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The Cosine Law is similar to the Pythagorean Theorem.
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c^2 = a^2 + b^2
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Add 1 term:
c^2 = a^2 + b^2 - 2ab*cos(C)
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Notice that angle C = 90 degs in a right triangle --> 2ab*0 --> Pythagoras.