Vectors Question 192

Question: The three vectors $ \vec{A}=3\hat{i}-2\hat{j}-\hat{k}, $ $ \vec{B}=\hat{i}-3\hat{j}+5\hat{k} $ and $ \vec{C}=2\hat{i}-\hat{j}-4\hat{k} $ does not form

Options:

A) an equilateral triangle

B) isosceles triangle

C) a right angled triangle

D) no triangle

Show Answer

Answer:

Correct Answer: A

Solution:

[a] $ \vec{A}=3\hat{i}-2\hat{j}+\hat{k},,\vec{B}=\hat{i}-3\hat{j}+5\hat{k},,\vec{C}=2\hat{i}-\hat{j}+4\hat{k} $ $ |\vec{A}|=\sqrt{3^{2}+{{(-2)}^{2}}+1^{2}}=\sqrt{9+4+1}=\sqrt{14} $ $ |\vec{B}|=\sqrt{1^{2}+{{(-3)}^{2}}+5^{2}}=\sqrt{1+9+25}=\sqrt{35} $ $ |\vec{C}|=\sqrt{2^{2}+1^{2}+{{(-4)}^{2}}}=\sqrt{4+1+16}=\sqrt{21} $ As $ B=\sqrt{A^{2}+C^{2}} $

Therefore ABC will be right angled triangle.