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\title{ Math 300, Spring 2003\\

Writing for Mathematics}

\author{John Baldwin}

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\maketitle

\begin{Lemma}[Law of Cosines]

The Law of Cosines states that if the three sides of triangle have

lengths $a,b,c$ and if $\gamma$ is the angle opposite the side of

length $c$, then

$$c^2 = a^2 +b^2 - 2\cos \gamma.$$

In the special case that $\gamma$ is a right angle we obtain as a

corollary the Phythagorean Theorem:

$$c^2 = a^2 +b^2.$$

\end{Lemma}

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