Mathematics · Complex Numbers

JEE Main 2025 — 4 April, Evening Shift — Question 21

Let the product of ω1=(8+i)sin⁡θ+(7+4i)cos⁡θ\omega_{1}=(8+i) \sin \theta+(7+4 i) \cos \theta and ω2=(1+8i)sin⁡θ+(4+7i)cos⁡θ\omega_{2}=(1+8 i) \sin \theta+(4+7 i) \cos \theta be

α+iβ,i=−1\alpha+i \beta, i=\sqrt{-1}. Let pp and qq be the maximum and the minimum values of α+β\alpha+\beta respectively. Then p+p+ qq is

equal to:

  1. Option A:

    140

  2. Option B:

    150

  3. Option C:

    130

    Correct
  4. Option D:

    160

Answer: C

Step-by-step solution

ω1=(8sin⁡θ+7cos⁡θ)+i(sin⁡θ+4cos⁡θ)\omega_{1}=(8 \sin \theta+7 \cos \theta)+i(\sin \theta+4 \cos \theta)

ω2=(sin⁡θ+4cos⁡θ)+i(8sin⁡θ+7cos⁡θ)\omega_{2}=(\sin \theta+4 \cos \theta)+i(8 \sin \theta+7 \cos \theta)

α=(8sin⁡θ+7cos⁡θ)+(sin⁡θ+4cos⁡θ)\alpha=(8 \sin \theta+7 \cos \theta)+(\sin \theta+4 \cos \theta)

−(sin⁡θ+4cos⁡θ)+(8sin⁡θ+7cos⁡θ)=0-(\sin \theta+4 \cos \theta)+(8 \sin \theta+7 \cos \theta)=0

β=(8sin⁡θ+7cos⁡θ)2+(sin⁡θ+4cos⁡θ)2\beta=(8 \sin \theta+7 \cos \theta)^{2}+(\sin \theta+4 \cos \theta)^{2}

=65sin⁡2θ+65cos⁡2θ+56sin⁡2θ+4sin⁡2θ=65 \sin ^{2} \theta+65 \cos ^{2} \theta+56 \sin 2 \theta+4 \sin 2 \theta

=65+60sin⁡2θ=65+60 \sin 2 \theta

(α+β)max⁡=125=p(\alpha+\beta)_{\max }=125=p

(α+β)min⁡=5=q(\alpha+\beta)_{\min }=5=q

p+q=130p+q=130

Answer key and solution verified before publishing.

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Exam
JEE Main 2025
Subject
Mathematics
Chapter
Complex Numbers
Topic
Demoivre's Theorem and Roots of Unity
Let the product of ω 1 =(8+i) sin θ+(7+4 i) cos θ and ω 2 =(1+8 i)… | JEE Main 2025 PYQ with Solution · DhiX AI