Q56 / 90 · JEE Main 2024 (29 Jan Shift 2) · Mathematics

Let OA→=a→,OB→=12a→+4b→ and OC→=b→, where O is the origin. If S is the parallelogram with adjacent sides OA and OC, then area of the quadrilateral OABCarea of S is equal to _____

  • A
    6
  • B
    10
  • C
    7
  • Correct answer
    D
    8

Solution

Figure

Area of parallelogram, S=|a→×b→|

Area of quadrilateral = Area ∆OAB+Area ∆OBC

=12{|a→×(12a→+4b→)|+|b→×(12a→+4b→)|}

=12{|4a→×b→|+|12b→×a→|}

=12{4|a→×b→|+12|a→×b→|}

=162|a→×b→|

=8|(a→×b→)|

Ratio =8|(a→×b→)||(a→×b→)|=8

Hence, the correct answer is option: 'D'.

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