Question

Determine whether the following points are collinear or not: P (1,5), Q (2,3) and R (-2, -11)

Answer 1

Concept:
Application:

Here, $PQ=\sqrt{{(2-1)}^2+{(3-5)}^2}=\sqrt{5}$

$QR=\sqrt{{(-2-2)}^2+{(-11-3)}^2}=\sqrt{212}$

$RP=\sqrt{{(1+2)}^2+{(5-11)}^2}=\sqrt{265}$

As $PR\ne PQ+QR$, so P, Q and R are not collinear.