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$\vec A\, = \,(\hat i\, + \,\hat j)$ અને $\vec B\, = \,(2\hat i\, - \,\hat j)$ આપેલ છે. સમતલ સદિશ $\vec C$ નું મૂલ્ય શેના વડે આપવામાં આવે, કે જેથી $\vec A\cdot \vec C\, = \,\vec B\cdot \vec C\, = \vec A\cdot \vec B$ થાય?
$\sqrt {\frac{5}{9}} $
$\sqrt {\frac{10}{9}} $
$\sqrt {\frac{20}{9}} $
$\sqrt {\frac{9}{12}} $
Solution
$\begin{array}{l}
If\,\vec C = a\hat i + b\hat j\,then\,\vec A.\vec C = \vec A.\vec B\\
a + b = 1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,…\left( i \right)\\
\vec B.\vec C = \vec A.\vec B\\
2a – b = 1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,…\left( {ii} \right)\\
Solving\,equation\,\left( i \right)\,and\,\left( {ii} \right)\,\,we\,get\\
a = \frac{1}{3},\,b = \frac{2}{3}\\
Magnitude\,of\,coplanar\,vector,\\
\left| {\vec C} \right| = \sqrt {\frac{1}{9} + \frac{4}{9}} = \sqrt {\frac{5}{9}}
\end{array}$
Similar Questions
જો $\left| {\vec A } \right|\, = \,2$ અને $\left| {\vec B } \right|\, = \,4$ હોય, તો કોલમ $-II$માં આપેલા ખૂણાને અનુરૂપ કોલમ $-I$માં આપેલા યોગ્ય સંબંધ સાથે જોડો.
| કોલમ $-I$ | કોલમ $-II$ |
| $(a)$ $\vec A \,.\,\,\vec B \, = \,\,0$ | $(i)$ $\theta = \,{0^o}$ |
| $(b)$ $\vec A \,.\,\,\vec B \, = \,\,+8$ | $(ii)$ $\theta = \,{90^o}$ |
| $(c)$ $\vec A \,.\,\,\vec B \, = \,\,4$ | $(iii)$ $\theta = \,{180^o}$ |
| $(d)$ $\vec A \,.\,\,\vec B \, = \,\,-8$ | $(iv)$ $\theta = \,{60^o}$ |
