Question
Let $$\alpha ,\,\beta ,\,\gamma $$ be distinct real numbers. The points with position vectors $$\alpha \hat i + \beta \hat j + \gamma \hat k,\,\beta \hat i + \gamma \hat j + \alpha \hat k$$ and $$\gamma \hat i + \alpha \hat j + \beta \hat k$$
A.
are collinear
B.
form an equilateral triangle
C.
form a scalene triangle
D.
form a right-angled triangle
Answer :
are collinear
Solution :
$$\alpha ,\,\beta $$ and $$\gamma $$ be distinct real numbers
$$\alpha \hat i + \beta \hat j + \gamma \hat k\,;\,\beta \hat i + \gamma \hat j + \alpha \hat k\,;\,\gamma \hat i + \alpha \hat j + \beta \hat k$$
$$\overrightarrow a ,\,\overrightarrow b $$ and $$\overrightarrow c $$ are collinear
If $$a = \alpha ,\,b = \beta ,\,c = \gamma \,\,\,\left( {\because \,\alpha = \hat i + \hat j + \hat k} \right)$$