A polygon has 1325 diagonals. How many vertices does it have?
The formula for diagonals is d = n(n3)/2, where d is the # of
diagonals, and n is the # of sides (or vertices). Just solve for n...
2d=n(n3)
2d=n^23n
2650=n^23n
n^23n2650=0
Solve w/ the quadratic formula (I'm probably doing this more
complicated than necessary, but I'm too tired to find a better way...)
And, since you can only use the positive root,
the figure as 53 vertices.

Posted by Matt
on 20041208 03:26:27 