If x cos theta = y cos left(theta + frac{2 pi | vedclass

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(C) Let $x \cos 	heta = y \cos \left(	heta + \frac{2 \pi}{3}ight) = z \cos \left(	heta + \frac{4 \pi}{3}ight) = \lambda$ (where $\lambda 
eq 0

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(C) Let $x \cos 	heta = y \cos \left(	heta + \frac{2 \pi}{3}ight) = z \cos \left(	heta + \frac{4 \pi}{3}ight) = \lambda$ (where $\lambda 
eq 0$).Then,$\frac{1}{x} = \frac{\cos 	heta}{\lambda}$,$\frac{1}{y} = \frac{\cos \left(	heta + \frac{2 \pi}{3}ight)}{\lambda}$,and $\frac{1}{z} = \frac{\cos \left(	heta + \frac{4 \pi}{3}ight)}{\lambda}$.Summing these,we get $\frac{1}{x} + \frac{1}{y} + \frac{1}{z} = \frac{1}{\lambda} \left[ \cos 	heta + \cos \left(	heta + \frac{2 \pi}{3}ight) + \cos \left(	heta + \frac{4 \pi}{3}ight) ight]$.Using the identity $\cos A + \cos B = 2 \cos \left(\frac{A+B}{2}ight) \cos \left(\frac{A-B}{2}ight)$ for the first and third terms:$\cos 	heta + \cos \left(	heta + \frac{4 \pi}{3}ight) = 2 \cos \left(	heta + \frac{2 \pi}{3}ight) \cos \left(-\frac{2 \pi}{3}ight) = 2 \cos \left(	heta + \frac{2 \pi}{3}ight) \left(-\frac{1}{2}ight) = -\cos \left(	heta + \frac{2 \pi}{3}ight)$.Substituting this back into the sum:$\frac{1}{x} + \frac{1}{y} + \frac{1}{z} = \frac{1}{\lambda} \left[ -\cos \left(	heta + \frac{2 \pi}{3}ight) + \cos \left(	heta + \frac{2 \pi}{3}ight) ight] = \frac{1}{\lambda} (0) = 0$.

If $x \cos \theta = y \cos \left(\theta + \frac{2 \pi}{3}\right) = z \cos \left(\theta + \frac{4 \pi}{3}\right)$,then $\frac{1}{x} + \frac{1}{y} + \frac{1}{z} = $

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