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Provide solution for RD Sharma maths class 12 chapter 27 Straight Line in Space exercise 27.1 question 10 maths textbook solution

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Answer :-

\begin{aligned} &\frac{x-1}{1}=\frac{y+1}{2}=\frac{z-2}{-2} \\ &\vec{r}=(\hat{\imath}-\hat{\jmath}+2 \hat{k})+\lambda(\hat{\imath}+2 \hat{\jmath}-2 \hat{k}) \end{aligned}\\

Hint :-

\vec{r}=a+\lambda b

Given :-

The line passing through (1 , -1 , 2) and parallel to the line whose equation  \frac{x-3}{1}=\frac{y-1}{2}=\frac{z+1}{-2}

Solution :-

Cartesian Equation of a line passing through a point (1,-1,2) and parallel to line 

\frac{x-3}{1}=\frac{y-1}{2}=\frac{z+1}{-2} is

\frac{x-x_{1}}{a}=\frac{y-y_{1}}{b}=\frac{z-z_{1}}{c}

\left ( x_{1} ,y_{1},z_{1}\right ) is the point and a,b,c are the direction ratios of the parallel line.)

  \frac{x-1}{1}=\frac{y+1}{2}=\frac{z-2}{-2}is the required cartesian equation of the line.

Let,  \frac{x-1}{1}=\frac{y+1}{2}=\frac{z-2}{-2}=\lambda \text { (say) }

We know that

\begin{aligned} \vec{r} &=x \hat{\imath}-y \hat{\jmath}+z \hat{k} \\ &=(\lambda+1) \hat{\imath}+(2 \lambda-1) \hat{\jmath}+(-2 \lambda+2) \hat{k} \\ &=(\hat{\imath}-\hat{\jmath}+2 \hat{k})+\lambda(\hat{\imath}+2 \hat{\jmath}-2 \hat{k}) \end{aligned}is the required vector equation.

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