If the three lines
Question:
If the three lines $x-3 \mathrm{y}=\mathrm{p}, \mathrm{a} x+2 y=\mathrm{q}$ and $\mathrm{a} x+\mathrm{y}=\mathrm{r}$ form a right $-$ angled triangle then:
Correct Option:
Solution:
