Question

If $A = 3 \hat { i } + 4 \hat { j }$ and the vector having the same magnitude as B and parallel to A is

• A. $5 \hat { i } + 20 \hat { j }$
• B. $15 \hat { i } + 10 \hat { j }$
• C. $20 \hat { i } + 15 \hat { j }$
• D. $15 \hat { i } + 20 \hat { j }$

Answer 1

Answer: (D)

$15 \hat { i } + 20 \hat { j }$

Answer 2

$| B | = \sqrt { 7 ^ { 2 } + ( 24 ) ^ { 2 } }$ $= \sqrt { 625 }$ $= 25$

Unit vector in the direction of A will be $\hat { A } = \frac { 3 \hat { i } + 4 \hat { j } } { 5 }$

So required vector =$= 15 \hat { i } + 20 \hat { j }$