If p is the length of the perpendicular drawn from the origin to the line \(\rm \frac{x}{a}+\frac{y}{b}=1\), then which of the following is correct?
1
\(\rm \frac{1}{p^2}=\frac{1}{a^2}+\frac{1}{b^2}\)
2
\(\rm \frac{1}{p^2}=\frac{1}{a^2}-\frac{1}{b^2}\)
3
\(\rm \frac{1}{p}=\frac{1}{a}+\frac{1}{b}\)
4
\(\rm \frac{1}{p}=\frac{1}{a}-\frac{1}{b}\)