# Find out, whether point (8, 6), (3, 4) and (1, – 7) are collinear or not

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

To determine if three points are collinear or not determine the line passing through any two points and see if this line passes through the third point.

It has to be determined if the points (8, 6), (3, 4) and (1, -7) are collinear. First determine the equation of the line through (8, 6) and (3, 4). It is given by (y - 6)/(x - 8) = (4 - 6)/(3 - 8)

=> 5y - 30 = 2x - 16

=> 5y - 2x - 14 = 0

Substituting the coordinates of the third point (1, -7)

5*(-7) - 2*1 - 14

=> -35 - 2 - 14 = -51

This is not equal to 0.

The three points are not collinear.

chaobas | College Teacher | (Level 1) Valedictorian

Posted on

For the line to be co-linear the determinant should be zero. that if (x1,y1),(x2.y2) and (x3,y3) are the three points then

x1(y2-y3)+x2(y3-y1)+x3(y1-y2)=0

now the three points are (8, 6), (3, 4) and (1, – 7) so

8(4-(-7))+3(-7-6)+1(6-4)

8*11+3*(-13)+2

=51 which is not equal to zero.

hence the three points are not collinear.