Question 882262
{{{SA = 2*pi*r^2 + 2*pi*r*h}}}



{{{SA = 2*pi*4^2 + 2*pi*4*21}}}



{{{SA = 2*pi*16 + 2*pi*4*21}}} Here's where you made the mistake. You computed {{{4^2 = 8}}} when it *should* have been {{{4^2 = 16}}}



{{{SA = 2*16*pi + 2*4*21*pi}}}



{{{SA = 32*pi + 168*pi}}}



{{{SA = 200pi}}} <font color="red"><--- Exact Surface Area</font> (in terms of {{{pi}}})



{{{SA = 200*(3.14)}}} 



{{{SA = 628}}} <font color="blue"><--- Approximate Surface Area</font> (using the approximation *[Tex \Large \pi \approx 3.14])



Note: to get a better approximation, use more digits of {{{pi}}}.



Another Note: the units of the final answer are in square feet.