If a straight line is equally inclined at an angle $\theta$ with all the three coordinate axes, then $\tan…

If a straight line is equally inclined at an angle $\theta$ with all the three coordinate axes, then $\tan \theta=$
  1. $2 \sqrt{2}$
  2. $\sqrt{2}$
  3. $1$
  4. $1+\sqrt{5}$

Solution

Since the line is making equal angle $\theta$ with the 3 co-ordinate axes. Hence $\alpha=\beta=\gamma=\theta$ $ \therefore l=m=n=\cos \theta $ We know that, $l^2+m^2+n^2=1$ $ \begin{aligned} & \Rightarrow 3 l^2=1 \Rightarrow l=\frac{1}{\sqrt{3}} \\ & \Rightarrow \cos \theta=\frac{1}{\sqrt{3}} \Rightarrow \sin \theta=\frac{\sqrt{2}}{\sqrt{3}} \end{aligned} $ Hence $\tan \theta=\frac{\sin \theta}{\cos \theta}=\sqrt{2}$

Asked in: AP EAMCET 2023 (19 May Shift 1)

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