﻿ There are 15 points in a plane of which exactly 8 are collinear. Find the number of straight lines obtained by joining there points.    : Kaysons Education

# There Are 15 Points In A Plane Of Which Exactly 8 Are Collinear. Find The Number Of Straight Lines Obtained By Joining There Points.

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## Question

### Solution

Correct option is

78

For line we require two points. Therefore the numbers of lines which we can obtained is 16C2 = 105. Since 8 of these points lie on a straight line, we lose 8C2 = 28 lines and get just one line on which these points lie. Therefore, the number of lines is 105 – 28 + 1 = 78.

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