Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • NCERT
  • For two vectors A and B, |A + B| = |A - B| is always true when (a) \left | A \right |=\left | B \right |\neq 0 (b) \left | A \right |\perp \left | B \right |

For two vectors A and B, |A + B| = |A - B| is always true when

(a) \left | A \right |=\left | B \right |\neq 0

(b) \left | A \right |\perp \left | B \right |

(c) \left | A \right |= \left | B \right |\neq 0 and A and B are parallel or anti parallel

(d) when either \left | A \right | or \left | B \right | is zero.

Answers (1)

The answer is the option (b) and (d)

Explanation:

Given : \left | \vec{A}+\vec{B} \right |=\left | \vec{A}-\vec{B} \right |

Now we square both sides and open the brackets to get:

\left | \vec{A} \right |^{2}+\left | \vec{B} \right |^{2}+2\left | \vec{A} \right |\left | \vec{B} \right |\cos \theta =\left | \vec{A} \right |^{2}+\left | \vec{B} \right |^{2}-2\left | \vec{A} \right |\left | \vec{B} \right |\cos \theta

4\left | \vec{A} \right |\left | \vec{B} \right |\cos \theta=0

So, we have, \theta =90 degree and \left | \vec{A} \right |=\left | \vec{B} \right |=0

Hence option b and option d are correct.

Posted by

infoexpert24

View full answer

Similar Questions

Latest Question