Search any question & find its solution
Question:
Answered & Verified by Expert
If $|\vec{a}|=4,|\vec{b}|=5$, then the values of $k$ for which $\vec{a}+k \vec{b}$ is perpendicular to $\vec{a}-k \vec{b}$ are
Options:
Solution:
2391 Upvotes
Verified Answer
The correct answer is:
$\pm \frac{4}{5}$
$\begin{aligned} & (\vec{a}+k \vec{b}) \cdot(\vec{a}-k \vec{b})=0 \\ & \therefore|a|^2-k^2|b|^2=0 \\ & \therefore(4)^2-k^2(5)^2=0 \Rightarrow k= \pm \frac{4}{5}\end{aligned}$
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.