Question

ok, so my guess is n+1/2n=total, but i'm not sure...
A line segment can be drawn from each vertex of a polygon to every other vertex, forming the sides and diagonals of the polygon. A square, for example, has 4 sides and 2 diagonals. Using combinations, write an expression that would give you the total number of sides and diagonals for a polygon with n sides

Answer 1

You have n vertices

To form diagonals, you have n - 3 choices left over to connect that first selected vertex to another vertex (and form a diagonal)

So there are n(n-3)/2 diagonals in any n-gon. I'm dividing by 2 because we're counting each diagonal twice if we simply do n(n-3).

From there, add on 'n' and then simplify that expression (and tell me what you get)

Answer 2

why subtract 3 though

Answer 3

Say you have something like this

Answer 4

Now say I pick this vertex