Question:
Find the slope of the normal at the point ' $t$ ' on the curve $x=\frac{1}{t}, y=t$.
Solution:
Given that the curve $x=\frac{1}{t}, y=t$
$\frac{\mathrm{dx}}{\mathrm{dt}}=\frac{-1}{\mathrm{t}^{2}}, \frac{\mathrm{dy}}{\mathrm{dt}}=1$
$\therefore \frac{d y}{d x}=\frac{\frac{d y}{d t}}{\frac{d x}{d t}}=\frac{1}{\frac{-1}{t^{2}}}=-t^{2}$
Now, Slope of tangent $=-t^{2}$
Slope of normal $=\frac{-1}{\text { Slope of tangent }}=\frac{1}{t^{2}}$