Mathematics
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OpenStudy (heyitslizzy13):
can anyone explain this thoroughly ?
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OpenStudy (heyitslizzy13):
OpenStudy (anonymous):
i think i can
OpenStudy (anonymous):
first either we need a variable for the radius of the sphere, or else we can give it a number
your choice, it makes no difference
OpenStudy (heyitslizzy13):
r?
OpenStudy (anonymous):
ok that is a good choice
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OpenStudy (anonymous):
if the radius of the sphere is \(r\) do you know the volume of the sphere (in terms of \(r\)?)
OpenStudy (heyitslizzy13):
i have no idea
OpenStudy (anonymous):
ok then i will tell you although a quick google search gives it instantly it is \[A=\frac{4}{3}\pi r^3\]
OpenStudy (anonymous):
if the radius of the sphere is \(r\) then the length of the side of the cube is evidently \(2r\)
what is the volume of the cube?
OpenStudy (heyitslizzy13):
a^3?
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OpenStudy (anonymous):
yeah but \(a=2r\)
OpenStudy (heyitslizzy13):
8r^3?
OpenStudy (anonymous):
so \[(2r)^3=8r^2\] is volume of the cube right
OpenStudy (anonymous):
then divide and you are done
the \(r^3\) will cancel when you do that
OpenStudy (heyitslizzy13):
i'm so confused :/
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OpenStudy (anonymous):
they want the ratio of the volumes right?
OpenStudy (heyitslizzy13):
yes
OpenStudy (anonymous):
the cube has volume \(8r^3\) and the sphere has volume \(\frac{4}{3}\pi r^3\)
OpenStudy (anonymous):
the ratio is
\[\huge \frac{8r^3}{\frac{4}{3}\pi r^3}\]
OpenStudy (anonymous):
cancel the \(r^3\) and simplify the compound fraction
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OpenStudy (heyitslizzy13):
6/pi ?