<p>I'm probably an idiot for not knowing how to do this but these problems always get me.</p>
<p>What is the maximum number of distinct diagonals that can be drawn in the hexagon shown below?<br>
everyone knows what a hexagon looks like</p>
<p>First off, someone explain diagonals to me.</p>
<p>All of these possible combinations questions get me everytime! HELP!</p>
<p>Basically, a diagonal connects two vertices in a shape but doesn't include the sides.</p>
<p>So a hexagon has 6 vertices. You choose two of them: 6C2 = 15 (we use 6C2 and not 6P2 because the order we choose the vertices doesn't matter).</p>
<p>Now, remember, that if you choose two vertices and connect them, you will sometimes get the sides. So we don't want the 6 sides.</p>
<p>15 - 6 = 9.</p>
<p>I understand everything except the 6C2 and 6P2 business, what do those letters stand for?</p>
<p>Combination and Permutation</p>
<p>(n(n-3))/2</p>