## Answer Given –

A = (2,1,3)

B = (5,0,5)

C = (-4,3,-1)

**To prove – **A, B and C are collinear

**Formula to be used – **If P = (a,b,c) and Q = (a’,b’,c’),then the direction ratios of the line PQ is given by ((a’-a),(b’-b),(c’-c))

The direction ratios of the line AB can be given by ((5-2),(0-1),(5-3))

=(3,-1,-2)

Similarly, the direction ratios of the line BC can be given by ((-4-5),(3-0),(-1-5))

=(-9,3,-6)

**Tip – **If it is shown that direction ratios of AB=λ times that of BC , where λ is any arbitrary constant, then the condition is sufficient to conclude that points A, B and C will be collinear.

So, d.r. of AB

=(3,-1,-2)

=(-1/3)Χ(-9,3,-6)

=(-1/3)Хd.r. of BC

Hence, **A, B and C are collinear**