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April 18, 2014

April 18, 2014

Posted by **lilman** on Monday, April 30, 2012 at 9:33pm.

I know the formula is SA=LA+2B, but not sure how to plug in the numbers and get answers. Everytime I try I get wrong answer.

The cylinder has I assume radius 8in and height 20in.

possible answers

352piin^2

320piin^2

832piin^2

448piin^2

It's possible I may have the numbers switched around. Can someone please help?

- surface area -
**Reiny**, Monday, April 30, 2012 at 9:47pmVisualize opening up a can (cylinder) and flattening out the pieces.

Don't you have 2 circles + a rectangle ?

The length of the rectangle would be the circumference of the circle, which is 16π

total area = 2circles + 1 rectangle

= 2(π(8^2)) + (16π)(20)

= 128π + 320π = 448π

(the formula you stated was useless to me since You did not define what L, A, and B stand for)

- surface area -
**lilman**, Monday, April 30, 2012 at 10:12pmThank you I see where I messed up, it was on the second spot where you got 320.

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