How many diagonals does a polygon with 15 sides have, if one of its vertices does not connect to any diagonal? Choose the correct choice from the following choices:
A) 80
B) 90
C) 77
D) 88
E) 99
If I calculate it using the formulae, #diagonals = n (n-3)/2Each vertex sends of n-3 diagonals   n= 15-1 then 14*(14-3)/2= 
<gadget id="calculator">14*(14-3)/2</gadget>
<output>77</output>
77   77orrect Option:77
<result>C</result>
How many diagonals does a polygon with 15 sides have, if one of its vertices does not connect to any diagonal?