A diagonal of a polygon is an segment between two non-adjacent vertices of the polygon. How many diagonals does a regular 10-sided polygon have?  Choose the correct choice from the following
A) 875  B) 35  C) 1425  D) 2025  E) 2500

Rationale: "there ' s a direct formula for this . number of diagonals in a regular polygon = [ n * ( n - 3 ) ] / 2 , n = number of sides of the regular polygon . here , n = 10 . plugging it in , we get 35 diagonals ! answer ( b ) ."
Answer: B