Dana plans to cover this model of a half moon completely with silver foil.
( imagine a semicircle with a radius of 8 cm)

How many square centimeters of silver foil would Dana need to cover the model completely?

Question

Dana plans to cover this model of a half moon completely with silver foil.  
( imagine a semicircle with a radius of 8 cm)
 

 
How many square centimeters of silver foil would Dana need to cover the model completely?

anonymous · Answer

I got 402 but it is wrong

anonymous · Answer

100,48

anonymous · Answer

circle area:$$A=\pi*r ^{2}$$
since it is half moon: devide by 2

anonymous · Answer

is that 100.48?

anonymous · Answer

taking value for pi 3,14, yes

anonymous · Answer

but it said... cover the entire thing? the outside not the volume

anonymous · Answer

i understand it like if you would cut the chape of half moon from sheet of paper, and cover one of it's sides

anonymous · Answer

gotcha. can you look at this next one as well

jim_thompson5910 · Answer

SA = (half of outside) + (inside circular surface)

SA = (1/2)*pi*r^2 + pi*r^2

SA = (1/2)*4*pi*8^2 + pi*8^2

SA = 128*pi + 64*pi

SA = 192*pi


So the exact surface area is  192pi square cm

and it approximates to 603.18578948924 square cm (use a calculator)