Question

Determine if the points (1, 5), (2, 3) and (-2, -11) are collinear.


Do this sum with
area of triangle = 1/2
|x1. y1|
|x2. y2|
|x3. y3|
|x1. y1|





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Answer

Answer 1

Solution :

Let A(-1,-1) = (x1,y1),B(0,1)=(x2,y2),

C(1,3)=(x3,y3) are vertices of

Triangle ABC.

Area of ∆ABC

=1/2|x1(y2-y3)+x2(y3-y1)+x3(y1-y2)|

=1/2|(-1)[1-3]+0[3-(-1)]+1[-1-1]|

= 1/2| (-1)(-2)+0+1(-2)|

=1/2| 2 -2 |

= 1/2 × 0

= 0

Therefore ,

Area of ∆ABC = 0,

A , B and C points are collinear.

.

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