A semicircle has an area of 40Π. What is its diameter?

Question

A semicircle has an area of  40\pi . What is its diameter?

(A)  2√5 
(B)  2√10 
(C)  4√5 
(D)  4√10 
(E)  8√5

saukrit · Answer

The area of full Circle=40 pi Hence 
r^2= 80
r=4√5

Answer is c

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Archit3110 · Answer

area -= pi * r^2/2 = 40 pi
solve for r= √80 ; 4√5 ; diameter ; 8√5
IMO E

ManjariMishra · Answer

Area of the semicircle 
(Pi*r^2)/2 = 40pi
R^2= 80
R= 4√5

Diameter= 2r
That is 8√5
E

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Abhishek009 · Answer

\frac{r^2}{2} = 40π

Or,  πr^2 = 80π

Or,  r^2 = 80

Or,  r^2 = 2^4*5

Or,  r = 4*\sqrt{5}

So, Diameter will be Or,  8\sqrt{5} , Answer must be (E)

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