JEE Main 2017 · 2 Apr · Shift 1 · Mathematics Q73

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MathematicsSingle correct+4 / -1Question 73 of 90

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 :

12.5

Answer and worked solution

Official answer: B

$2r+r\theta=20$ , and the area is $\frac12r^2\theta=r(10-r)$ . This is largest at $r=5$ : 25 m².

Topics:Maxima and minima

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JEE Main 2017 · 2 Apr · Shift 1, Mathematics question 73