JEE Main 2017MathematicsApplication of DerivativesMediumMCQ

JEE Main 2017 — Application of Derivatives Question with Solution

JEE Main 2017 (02 Apr)

Question

Twenty meters of wire is available for fencing off a flower-bed in the form of a circular sector. Then the maximum area (in sq. m) of the flower-bed, is:

Choose an option

Show full solutionCorrect option: C
Correct answer
C25

Step-by-step explanation

Perimeter =2r+rθ=20



θ=20-2rr

Now, Area A=r2θ2

⇒A=r22 20-2rr=10r-r2

⇒dAdr=10-2r=0

⇒r=5

d2Adr2r=5=-2<0⇒r=5 is the point of maxima

Amax=10×5-25=25

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About this question

This is a previous-year question from JEE Main 2017, covering the Application of Derivatives chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.