Question:

20 meters of wire is available to fence of a flowerbed in the form of a circular sector. If the flowerbed is to have maximum surface area, then the radius of the circle is

Updated On: Jun 23, 2024
  • 8 m
  • 5 m
  • 2 m
  • 4 m
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The Correct Option is B

Solution and Explanation

Sector of a circle = 2l+r 
2r+l = 20
l = 20 -2r 
Area = \(\frac {1}{2}\)lr 
Area = \(\frac {1}{2}\)*(20-2r)*r = 10r - r
Now
dA/dx = 10 - 2r 
10 - 2r = 0 
r = 5 m

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Concepts Used:

Maxima and Minima

What are Maxima and Minima of a Function?

The extrema of a function are very well known as Maxima and minima. Maxima is the maximum and minima is the minimum value of a function within the given set of ranges.

There are two types of maxima and minima that exist in a function, such as:

  • Local Maxima and Minima
  • Absolute or Global Maxima and Minima