How many diagonals does a pentagon have?

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Accepted Answer

1. A diagonal joins two non-adjacent vertices.

2. For an $n$-sided polygon the formula is $\dfrac{n(n-3)}{2}$.

3. For a pentagon $n=5$, so $\dfrac{5(5-3)}{2}=\dfrac{5	imes2}{2}=5$.

4. Thus, a pentagon has 5 diagonals.

FINAL_ANSWER: a

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