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JEE Main 202429 JanuaryEvening Shift
Exam
JEE Main
Year
2024
Date
29 January
Shift
Evening Shift
Subject
Mathematics
Chapter
Vector Algebra

JEE Main 2024 · 29 January · Evening Shift · Mathematics · Vector Algebra

Let → OA = → a , → OB = 12 → a + 4 → b and → OC = → b , where O is...

Let OA→=a→,OB→=12a→+4b→\overset{\to}{OA} = \overset{\to}{a}, \overset{\to}{OB} = 12\overset{\to}{a} + 4\overset{\to}{b} and OC→=b→\overset{\to}{OC} = \overset{\to}{b}, where OO is the origin. If SS is the parallelogram with adjacent sides OAOA and OCOC, then areaofthequadrilateralOABCareaofS\dfrac{areaofthequadrilateralOABC}{areaofS} is equal to _____Let → OA = → a , → OB = 12 → a + 4 → b and → OC = → b , where O is the origin. If S is the parallelogram with adjacent

Options

  1. A66
  2. B1010
  3. C77
  4. D88

Correct answer

D. 88

Step-by-step solution

Let → OA = → a , → OB = 12 → a + 4 → b and → OC = → b , where O is the origin. If S is the parallelogram with adjacent

Area of parallelogram, S=∣a→×b→∣S = | \overset{\to}{a} \times \overset{\to}{b} |

Area of quadrilateral = Area \left(∆ OAB\right) +Area (∆OBC)Area \left(∆ OBC\right)

=12∣a→×(12a→+4b→)∣+∣b→×(12a→+4b→)∣= \dfrac{1}{2} { | \overset{\to}{a} \times ( 12\overset{\to}{a} + 4\overset{\to}{b} ) | + | \overset{\to}{b} \times ( 12\overset{\to}{a} + 4\overset{\to}{b} ) | }

=12∣4a→×b→∣+∣12b→×a→∣= \dfrac{1}{2} { | 4\overset{\to}{a} \times \overset{\to}{b} | + | 12\overset{\to}{b} \times \overset{\to}{a} | }

=124∣a→×b→∣+12∣a→×b→∣= \dfrac{1}{2} { 4 | \overset{\to}{a} \times \overset{\to}{b} | + 12 | \overset{\to}{a} \times \overset{\to}{b} | }

=162∣a→×b→∣= \dfrac{16}{2} | \overset{\to}{a} \times \overset{\to}{b} |

=8∣(a→×b→)∣= 8 | ( \overset{\to}{a} \times \overset{\to}{b} ) |

Ratio =8∣(a→×b→)∣∣(a→×b→)∣=8= \dfrac{8 | ( \overset{\to}{a} \times \overset{\to}{b} ) |}{| ( \overset{\to}{a} \times \overset{\to}{b} ) |} = 8

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