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3-1.Vectors
medium
$\mathop P\limits^ \to $ तथा $\mathop Q\limits^ \to $ का परिणामी $\mathop P\limits^ \to $ के लम्बवत् है तो $\mathop P\limits^ \to $ तथा $\mathop Q\limits^ \to $ के बीच कोण होगा
A
${\cos ^{ - 1}}(P/Q)$
B
${\cos ^{ - 1}}( - P/Q)$
C
${\sin ^{ - 1}}\,(P/Q)$
D
${\sin ^{ - 1}}\,( - P/Q)$
Solution
(b) $\tan 90^\circ = \frac{{Q\sin \theta }}{{P + Q\cos \theta }}$
$⇒$ $P + Q\cos \theta = 0$
$\cos \theta = \frac{{ – P}}{Q}$
$⇒$ $\theta = {\cos ^{ – 1}}\left( {\frac{{ – P}}{Q}} \right)$
Standard 11
Physics
