Q13 of 184 Page 10

If the points (a, b), (a1, b1) and (a-a1, b-b1) are collinear, show that

Given (a, b), (a1, b1) and (a-a1, b-b1)


We know the points are collinear if area(∆ABC)=0


Area of triangle


Then, Area



{ab + a1 b1} = ab – ab1 – a1 b + a1 b1


- ab1 - a1b = 0


-ab1 = a1b


Therofe, We can write as



Hence, Proved.


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