Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Vectors

Question:

Statement-1: If $\vec a=\hat i+\hat j+\hat k$ and $\vec b=2\hat i+2\hat j$, then component of $\vec a$ orthogonal to $\vec b$ is $\hat k$.

Statement-2: Component of $\vec a$ along $\vec b=\frac{(\vec a.\vec b)}{|\vec b|^2}\vec b$ and component of $\vec a$ orthogonal to $\vec b$ is $\vec a-(\frac{\vec a.\vec b}{|\vec b|^2})\vec b$.

Options:

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1. 

Statement-1 is True, Statement-2 is True; Statement-2 is not a correct explanation for Statement-1. 

Statement-1 is True, Statement-2 is False.

Statement-1 is False, Statement-2 is True.

Correct Answer:

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1. 

Explanation:

Clearly, statement-2 is true.

We have, $\vec a.\vec b=2+2=4, |\vec b|^2=8$

Using statement-2, we have

Component of $\vec a$ orthogonal to $\vec b=\vec a-\frac{(\vec a.\vec b)}{|\vec b|^2}\vec b$

$=\vec a-\frac{1}{2}\vec b$

$=(\hat i+\hat j+\hat k)-(\hat i+\hat j)=\hat k$

So, statement-1 is true.

Also, statement-2 is a correct explanation for statement-1.