If x 0, y 0 and z 0 and 1x^2 + 1y^2 + 1z^2 = 1xy + 1yz + 1zx then the relation among x, y, z is?

Answer: Option D

$$\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2}=\frac{1}{xy}+\frac{1}{yz}+\frac{1}{zx}$$
Go through option D take x = y = z
$$\begin{array}{rl}& \frac{1}{x^2}+\frac{1}{x^2}+\frac{1}{x^2}=\frac{1}{x^2}+\frac{1}{x^2}+\frac{1}{x^2}\\ & \therefore \text{Option ’D’ is right}\end{array}$$