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The line of shortest distance between the lines \mathrm{\frac{x-2}{0}=\frac{y-1}{1}=\frac{z}{1}}  and  \mathrm{\frac{x-3}{2}=\frac{y-5}{2}=\frac{z-1}{1}} makes an angle of  \mathrm{\cos ^{-1}\left(\sqrt{\frac{2}{27}}\right)} with the plane \mathrm{\mathrm{P}: \mathrm{a} x-y-z=0},\mathrm{(a>0)}. If the image of the point \mathrm{(1,1,-5)} in the plane \mathrm{P} is \mathrm{(\alpha, \beta, \gamma)}, then \mathrm{\alpha+\beta-\gamma} is equal to ________.

Option: 1

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Option: 2

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Option: 3

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Option: 4

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Answers (1)

best_answer

DR's of line of shortest distance

\mathrm{\left|\begin{array}{ccc} \hat{i} \cdot \hat{j} & \hat{k} \\ 0 & 1 & 1 \\ 2 & 2 & 1 \end{array}\right|=-\hat{i}+2 \hat{J}-2 k^{r}}

angle between line and plane is \mathrm{\cos ^{-1} \sqrt{\frac{2}{27}}=\alpha}

\mathrm{\cos \alpha=\sqrt{\frac{2}{27}}, \quad \sin \alpha=\frac{5}{3 \sqrt{3}}}

DR's normal to plane (1,-1,-1)

\sin \alpha=\left|\frac{-a-2+2}{\sqrt{4+4+1} \sqrt{a^{2}+1+1}}\right|=\frac{5}{3 \sqrt{3}} \\

\mathrm{\sqrt{3}|a|=5 \sqrt{a^{2}+2}} \\

\mathrm{3 a^{2}=25 a^{2}+50} \\

\text { No value of } a

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manish

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