Mathematics · Functions

JEE Main 2024 — 8 April, Shift 1 — Question 26

If the range of f(θ)=sin⁡4θ+3cos⁡2θsin⁡4θ+cos⁡2θ,θ∈Rf(\theta)=\frac{\sin ^{4} \theta+3 \cos ^{2} \theta}{\sin ^{4} \theta+\cos ^{2} \theta}, \theta \in \mathbb{R} is [α,β][\alpha, \beta], then the sum of the infinite G.P., whose first term is 64 and the common ratio is αβ\frac{\alpha}{\beta}, is equal to \qquad

Answer: 96

Numerical answer — enter this value.

Step-by-step solution

f(θ)=sin⁡4θ+3cos⁡2θsin⁡4θ+cos⁡2θf(\theta)=\frac{\sin ^{4} \theta+3 \cos ^{2} \theta}{\sin ^{4} \theta+\cos ^{2} \theta}

f(θ)=1+2cos⁡2θsin⁡4θ+cos⁡2θf(\theta)=1+\frac{2 \cos ^{2} \theta}{\sin ^{4} \theta+\cos ^{2} \theta}

f(θ)=2cos⁡2θcos⁡4θ−cos⁡2θ+1+1f(\theta)=\frac{2 \cos ^{2} \theta}{\cos ^{4} \theta-\cos ^{2} \theta+1}+1

f(θ)=2cos⁡2θ+sec⁡2θ−1+1f(\theta)=\frac{2}{\cos ^{2} \theta+\sec ^{2} \theta-1}+1

f(θ)∣min⁡.=1\left.\mathrm{f}(\theta)\right|_{\min .}=1

f(θ)max. =3\mathrm{f}(\theta)_{\text {max. }}=3

S=641−1/3=96\mathrm{S}=\frac{64}{1-1 / 3}=96

Answer key and solution verified before publishing.

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Exam
JEE Main 2024
Subject
Mathematics
Chapter
Functions
Topic
Domain & range of functions
If the range of f(θ)=frac sin 4 θ+3 cos 2 θ sin 4 θ+cos 2 θ , θ in… | JEE Main 2024 PYQ with Solution · DhiX AI