Twenty eight meters of wire is available to fence off a flower bed in the form of a circular sector. What must the radius of the circle in meters be, if we wish to have a flower bed with the greatest possible surface area? Choose the correct choice from the following options
A) 2√2  B) 2√5  C) 5  D) 7  E) none of these
Area of Sector, A = x/360*pi*r^2   Circumference of the sector = 28   =&gt; x/360*2*pi*r +2r= 28   =&gt; 2A/r+2r=28   =&gt; A= r14-r^2   = r14-r^2   We will now max using derivations   Max value of A will found at A=0   i.e 14-2r=0   r=7   7
<result>D</result>
Twenty eight meters of wire is available to fence off a flower bed in the form of a circular sector. What must the radius of the circle in meters be, if we wish to have a flower bed with the greatest possible surface area?