You can also use the Law of Cosines with triangles determined by the measures of all three sides (SSS).
What is the measure of
Think | Write |
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Choose the form of the Law of Cosines that contains
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Substitute and simplify. |
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Combine like terms. |
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Solve for cos C. |
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Solve for
Use a calculator. |
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Sometimes you need to use the Law of Cosines followed by the Law of Cosines again or by the Law of Sines.
In
Step 1 Draw a diagram.
How do you start?
Drawing a diagram makes it easier to see what you know and what you are looking for.
Step 2 Find a. Since you cannot find