Verified Solution • 2025–26 Session moderate

QJEEM21Ma11ee: JEE Main 2021 Physics - Class 11 JEEM21Ma11ee Solution: Let a, b and c be distinct positive numbers. If the vectors and …

Let a, b and c be distinct positive numbers. If the vectors ai^+aj^+ck^,i^+k^a\widehat i + a\widehat j + c\widehat k,\widehat i+\widehat k and ci^+cj^+bk^c\widehat i + c\widehat j + b\widehat k are co-planar, then c is equal to :

Multiple Choice Options

  • A 21a+1b{2 \over {{1 \over a} + {1 \over b}}}
  • B a+b2{{a + b} \over 2}
  • C 1a+1b{1 \over a} + {1 \over b}
  • D ab\sqrt {ab}

Step-by-Step Verified Solution

Because vectors are coplanar

Hence, |aac101ccb|=0

⇒c2=ab⇒c=ab\Rightarrow {c^2} = ab \Rightarrow c = \sqrt {ab}

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