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3-1.Vectors
medium
$\left( {\,{\rm{2\hat i}}\,\, + \;\,{\rm{3\hat j}}\,\, + \;\,{\rm{\hat k}}\,} \right)$ અને $\left( {\, - 3\hat i\,\, + \;\,6\hat k\,} \right)$ બે સદીશો વચ્ચેનો ખૂણો ...... $^o$ હોય.
A
$0$
B
$45$
C
$60$
D
$90$
Solution
$cos\theta \,\, = \,\,\frac{{\mathop {\rm{A}}\limits^ \to \,\mathop {\rm{B}}\limits^ \to }}{{|\mathop {\rm{A}}\limits^ \to |\,\,|\mathop {\rm{B}}\limits^ \to |}}\,\, = \,\,\frac{{ – 6\,\, + \;\,6}}{{\sqrt {14} \,\,\sqrt {45} }}\,\, = \,\,0\,\,\,\, \Rightarrow \,\,\theta \,\, = \,\,90^\circ $
Standard 11
Physics
