If $\hat{i}-2 \hat{j}+3 \hat{k}, 2 \hat{i}+3 \hat{j}+\hat{k},-3 \hat{i}-\hat{j}-2 \hat{k}$ are the position…

If $\hat{i}-2 \hat{j}+3 \hat{k}, 2 \hat{i}+3 \hat{j}+\hat{k},-3 \hat{i}-\hat{j}-2 \hat{k}$ are the position vectors of three points A, B, C respectively, then $\mathrm{A}, \mathrm{B}, \mathrm{C}$
  1. are collinear points
  2. form an isosceles triangle which is not equilateral
  3. form an equilateral triangle
  4. form a scalene triangle

Solution

$\overrightarrow{A B}=\hat{i}+5 \hat{j}-4 \hat{k}, \overrightarrow{B C}=-5 \hat{i}-4 \hat{j}-\hat{k}$ $\overrightarrow{A C}=-4 \hat{i}+\hat{j}-5 \hat{k} \quad \therefore|\overrightarrow{A B}|=|\overrightarrow{B C}|=|\overrightarrow{A C}|=\sqrt{42}$ $\therefore A, B, C$ form an equilateral triangle.

Asked in: AP EAMCET 2024 (21 May Shift 2)

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