Question:
Show that the points $A, B$ and $C$ having position vectors $(3 \hat{\mathrm{i}}-4 \hat{\mathrm{j}}-4 \hat{\mathrm{k}}),(2 \hat{\mathrm{i}}-\hat{\mathrm{j}}+\hat{\mathrm{k}})$ and $(\hat{\mathrm{i}}-3 \hat{\mathrm{j}}-5 \hat{\mathrm{k}})$ respectively, form the vertices of a right-angled triangle.
Solution:
