## Geometry: Common Core (15th Edition)

If n is the number of points, then $\frac{n(n-1)}{2}$ is the number of segments. You can therefore plug 8 in for n and then solve to get 28: $\frac{8(8-1)}{2}$= $\frac{8(7)}{2}$ = $\frac{56}{2}$ = 28