The length of the perpendicular from the point $(0,2,3)$ on the line…

The length of the perpendicular from the point $(0,2,3)$ on the line $\frac{x+3}{5}=\frac{y-1}{2}=\frac{z+4}{3}$
  1. $\sqrt{15}$ units
  2. $\sqrt{21}$ units
  3. $\sqrt{33}$ units
  4. $\sqrt{11}$ units

Solution

Any point on the line $\frac{x+3}{5}=\frac{y-1}{2}=\frac{z+4}{3}=\lambda$ can be taken as $(5 \lambda-3,2 \lambda+1,3 \lambda-4)$ $\begin{aligned} & \text { for foot of perpendicular } \lambda=\frac{a\left(\alpha-x_1\right)+b\left(\beta-y_1\right)+c\left(\gamma-z_1\right)}{a^2+b^2+c^2} \\ & =\frac{5(0+3)+2(2-1)+3(3+4)}{5^2+2^2+3^2} \\ & \text { i.e., } \lambda=1 \\ & \Rightarrow \text { foot of perpendicular }(2,3,-1) \\ & \Rightarrow \text { Length of the perpendicular }=\sqrt{(0-2)^2+(2-3)^2+(3+1)^2} \\ & =\sqrt{21} \end{aligned}$

Asked in: MHT CET 2022 (10 Aug Shift 1)

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