Solve the Problem $$\frac { 1 } { 2 } n ( n - 3 )$$

question 134

Multiple Choice

Solve the problem.
-If a polygon, of n sides has $$\frac { 1 } { 2 } n ( n - 3 )$$ ) diagonals, how many sides will a polygon with 189 diagonals have?

• A) 22 sides
• B) 21 sides
• C) 20 sides
• D) 23 sides