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3-1.Vectors
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The angles which the vector $A =3 \hat{ i }+6 \hat{ j }+2 \hat{ k }$ makes with the coordinate axes are
A$\cos ^{-1} \frac{3}{7}, \cos ^{-1} \frac{6}{7}$ and $\cos ^{-1} \frac{2}{7}$
B$\cos ^{-1} \frac{4}{7}, \cos ^{-1} \frac{5}{7}$ and $\cos ^{-1} \frac{3}{7}$
C$\cos ^{-1} \frac{3}{7}, \cos ^{-1} \frac{4}{7}$ and $\cos ^{-1} \frac{1}{7}$
DNone of the above
Solution
(a)
$A=\sqrt{9+36+4}=7$
$\therefore \quad \alpha=\cos ^{-1}\left(\frac{3}{7}\right)$ etc.
$A=\sqrt{9+36+4}=7$
$\therefore \quad \alpha=\cos ^{-1}\left(\frac{3}{7}\right)$ etc.
Standard 11
Physics
