SOLUTION: In a triangle ABC with side a=6, side b=8, side c= 13, what the measure of angle C?

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Question 1197887: In a triangle ABC with side a=6, side b=8, side c= 13, what the measure of angle C?
Found 2 solutions by MathLover1, Alan3354:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

use the law of cosines
cos%28C%29+=+%28a%5E2+%2B+b%5E2+-+c%5E2%29%2F%282ab%29
cos%28C%29+=+%286%5E2+%2B+8%5E2+-+13%5E2%29%2F%282%2A6%2A8%29
cos%28C%29+=+-69%2F96
cos%28C%29+=+-23%2F32
C+=+cos%5E-1%28-23%2F32%29
C+=+2.3727991 rad. or C+=+136°


Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
In a triangle ABC with side a=6, side b=8, side c= 13, what the measure of angle C?
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If angle C is opposite side c:
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Use the Cosine Law:
c%5E2+=+a%5E2+%2B+b%5E2+-+2ab%2Acos%28C%29