How many triangles can be formed by a diagonal drawn from a fixed vertex of a polygon with 17 sides?

In a polygon with 17 sides, a diagonal can be drawn from a fixed vertex to any of the other non-adjacent vertices. From one vertex, there are 14 other vertices (17 total vertices - 1 fixed vertex - 2 adjacent vertices) to which diagonals can be drawn. Each diagonal creates a triangle with the fixed vertex and two of the vertices connected by the diagonal. Therefore, the number of triangles that can be formed is equal to the number of diagonals, which is 14.