Practicing Success
Practicing Success
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If \(\left|\vec{a}\times \vec{b}\right|^{2}+\left|\vec{a}\cdot \vec{b}\right|^{2}=144\) and \(\left|\vec{a}\right|=4\) then \(\left|\vec{b}\right|\) is equal to |
\(12\) \(8\) \(4\) \(3\) |
\(3\) |
| \(\begin{aligned}\left|\vec{a}\times \vec{b}\right|^{2}+\left|\vec{a}\cdot \vec{b}\right|^{2}&=\left|a\right|^{2}\left|b\right|^{2}\\ 144&=16|\vec{b}|^{2}\\ |\vec{b}|^{2}&=9\\ |\vec{b}|&=3\end{aligned}\) |
