1. Copyright 2013 Davitily

2. Find a Missing Side Using the Law of CosinesB
Step 1:
Apply the Law of Cosines to the triangle.
Step 2:
Select which formula to use.
Step 3:
Solve for the unknown. a b C
a 2 = b 2 + c 2 −2bc⋅cos A b 2 = a 2 + c 2 −2ac⋅cos B c 2 = a 2 + b 2 −2ab⋅cos C
a 2 = − ⋅cos o
Step 1:
Apply the Law of Cosines to the triangle.
a 2 = −646⋅cos o
Step 2:
Select which formula
to use.
Step 3:
Solve for the unknown.
a 2 = −416.10
a 2 =233.9 a=
=15.294=15.3

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