Chapter B, Problem 14E

  $\left(a\right)$

To determine

Show that the points $A\left(-1,3\right)\text{, }B\left(3,11\right)\text{ and }C\left(5,15\right)$ are collinear by showing that $\left|AB\right|+\left|BC\right|=\left|AC\right|$ .

  $\left(b\right)$

To determine

Show that the points $A\left(-1,3\right)\text{, }B\left(3,11\right)\text{ and }C\left(5,15\right)$ are collinear by showing that $\left|AB\right|+\left|BC\right|=\left|AC\right|$ .