Law of cosines: a2 = b2 + c2 – 2bccos(a)

which equation correctly uses the law of cosines to solve for the missing side length of pqr?

62 = p2 + 82 – 2(p)(8)cos(39°)
p2 = 62 + 82 – 2(6)(8)cos(39°)
82 = 62 + p2 – 2(6)(p)cos(39°)
p2 = 62 + 62 – 2(6)(6)cos(39°)

The law of Cosines:





Since we have a SAS triangle, we can use

In the law above, pretend C and is P and
a = 6 and b = 8

So this tells us that the second one it the correct answer.

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