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MHT CET · Maths · Three Dimensional Geometry

If cartesian equation of the line is \(x-1=2 y+3=3-z\), then its vector equation
is

  1. A \(\bar{r}=(\hat{\imath}-3 \hat{\jmath}+3 \hat{k})+\lambda(2 \hat{\imath}+\hat{\jmath}-2)\)
  2. B \(\bar{r}=(-\hat{\imath}-3 \hat{\jmath}+3 \hat{k})+\lambda\left(\hat{\imath}+\frac{1}{2} \hat{\jmath}-\hat{k}\right)\)
  3. C \(\bar{r}=\left(-\hat{\imath}+\frac{3}{2} \hat{\jmath}-3 \hat{k}\right)+\lambda(2 \hat{\imath}+\hat{\jmath}-2 \hat{k})\)
  4. D \(\bar{r}=\left(\hat{\imath}-\frac{3}{2} \hat{\jmath}+3 \hat{k}\right)+\lambda(2 \hat{\imath}+\hat{\jmath}-2 \hat{k})\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\bar{r}=\left(\hat{\imath}-\frac{3}{2} \hat{\jmath}+3 \hat{k}\right)+\lambda(2 \hat{\imath}+\hat{\jmath}-2 \hat{k})\)

Step-by-step Solution

Detailed explanation

Given Cartesian equation is
\(x-1 =2 y+3=3-z \)
\( \therefore \frac{x-1}{1} =\frac{2\left(y+\frac{3}{2}\right)}{1}=\frac{-(z-3)}{1} \Rightarrow \frac{x-1}{1}=\) \(\frac{y+\frac{3}{2}}{\left(\frac{1}{2}\right)}=\frac{z-3}{-1}\)
\(\therefore 1, \frac{1}{2},-1 \text { i.e. } 2,1,-2 \text { are d.r. of given line. } \)
\( \therefore \mathrm{A}\left(1,-\frac{3}{2}, 3\right) \text { lies on given line. } \)
\( \therefore \text { vector equation is } \)
\(\overline{\mathrm{r}}=\overline{\mathrm{a}}+\lambda \overline{\mathrm{b}}=\left(\hat{\mathrm{i}}-\frac{3}{2} \hat{\mathrm{j}}+3 \hat{\mathrm{k}}\right)+\lambda(2 \hat{\mathrm{i}}+\hat{\mathrm{j}}-2 \hat{\mathrm{k}})\)