Question

Find the total surface.....
number 30 in attached file

Answer 1

can you find the area of the rings on the top and bottom?

Answer 2

after you get that, just add the lateral surface area of the outside and inside of the cylinder

Answer 3

@dpaInc I am having trouble with finding the areas.

Answer 4

ok. do you know what I'm talking about as far as the rings are concerned?

Answer 5

yes

Answer 6

so, as far as the rings go, the outer diameter is 10 and the inner diameter is 8, or outer radius is 5 and inner radius is 4.

so the area of the ring is area of the bigger circle - area of smaller circle
Use pi*r^2 for the area... what do you get? in terms of pi...

Answer 7

still there?

Answer 8

area of the big circle = pi*(5^2) = 25*pi
area of the small circle = pi*(4^2) = 16*pi
So area of the ring is...

Answer 9

@dpaInc so its 25pie-16pie

Answer 10

yes, simply 9pi. but since you have two of them (top and bottom) the area of the two rings combined is 18pi.
Now all you have to do is add the lateral surface areas of the inside and outside of the cylinder.