Search any question & find its solution
Question:
Answered & Verified by Expert
If two vectors $\vec{a}$ and $\vec{b}$ which are perpendicular to each other are such that $|\vec{a}|=8$ and $|\vec{b}|=3$, then $|\vec{a}-2 \vec{b}|=$
Options:
Solution:
1041 Upvotes
Verified Answer
The correct answer is:
$10$
$\begin{aligned} & |\vec{a}|=8,|\vec{b}|=3 \\ & \vec{a} \cdot \vec{b}=0 \\ & |\vec{a}-2 \vec{b}|^2=(\vec{a}-2 \vec{b}) \cdot(\vec{a}-2 \vec{b}) \\ & =|\vec{a}|^2+4|\vec{b}|^2-4 \vec{a} \cdot \vec{b} \\ & =64+36=100 \\ & \therefore \quad|\vec{a}-2 \vec{b}|=10 \text {. } \\ & \end{aligned}$
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.