- #1

sankalpmittal

- 785

- 25

## Homework Statement

In a polygon , no three diagonals are concurrent. If the total number of points of intersection of diagonals interior to the polygon be 70 , then find the number of diagonals of the polygon.

(You must get a numerical value..)

## Homework Equations

Number of diagonals of polygon =

^{n}C

_{2}-n

## The Attempt at a Solution

I tried doing experiment on this question :

Quadrilateral : 2 diagonals : 1 point of intersection

Pentagon : 5 diagonals : 5 points of intersection

Hexagon : 9 diagonals : 13 points of intersection

.

.

.

.

I expected that this will be forming some sort of series , but this did not happen. Also , I tried putting

^{n}C

_{2}= 70 and tried every sort of this thing.

Please help !

Thanks in advance...