An octagon has 8 sides. How many diagonals does an octagon have?
Little confused with this question. . can anyone help?
Thanks
Originally Posted by Carrick
The above quote is from a PM: please ask such questions in the open. Others may also benefit from the answer.
An octagon is a figure with eight vertices and eight edges. If two edges share a vertex, then the edges are said to be adjacent. But any two vertices will determine a line segment. If you join each vertex with each other vertex we have what is known as a complete graph. In the case of eight vertices the complete graph, , has 28 edges. The diagonals are the edges that are in the original octagon. Thus 20 are diagonals.
Thus in there are edges.
But n of the edges are not diagonals.