If p^a = q^b = r^c and pqr= 1 prove that 1/a +1/b+1/c = 0.

Q. In the Figure, PA, QB and RC are perpendicular to AC. Prove that $\frac{1}{x}+\frac{1}{z}=\frac{1}{y}$.

Q.

In Fig. 7.145, PA, QB and RC are each perpendicular to AC. Prove that $\frac{1}{x}+\frac{1}{z}=\frac{1}{y}$

Q. In the given figure, PA, QB and RC are each perpendicular to AC. Prove that $\frac{1}{x}+\frac{1}{z}=\frac{1}{y}$.

Q. If $p+q+r=0$, then prove that

Q. If $p+q+r=0,$ prove that
$\left|\begin{array}{ccc}pa& qb& rc\\ qc& ra& pb\\ rb& pc& qa\end{array}\right|=pqr\left|\begin{array}{ccc}a& b& c\\ c& a& b\\ b& c& a\end{array}\right|$