Question

there are 10 points in a plane out of which 4 are collinear , the maximum number of straight lines that can be drawn from these points will be:

1)40

2)45

3)46

4)36

IS THERE ANY FORMULA FOR THIS KIND OF QUESTIONS?

Answer 1

it is a simple combination question

2 points when joined in a plane will make 1 line.

If the total number of point is 10, the total number of line = 10C2

But 4 points are collinear, so the lines make with these 4 points are same.

Hence there is 1 common line joining the 4 collinear point.

Finally, the number of straight line = 10C2 - 4C2 + 1 = 45 - 6 + 1 = 40