Question

There are n points on a circle .the number of straight lines obtained by joining these is

Answer 1

Any 3 points in a circle, they will never be collinear.
In a circle, we can form straight lines by joining  maximum or minimum 2 points at a time.

Hence, number of straight lines obtained by n points of  circle will be $^{n} C_{2}$

Answer 2

Hi ,

Number of points on a circle = n

number of straight lines obtained

by joining 2 points at a time = nC2

I hope this helps you.

: )