Question

what is the total surface area of a cylinder with a radius of 4, and a height of 12. But, each end of the cylinder has a half-sphere.
HELP!

Answer 1

so basically the area of a sphere + the area of the side face of the cylinder

Answer 2

what?? its half a sphere.

Answer 3

side face is otherwise known as lateral area

Answer 4

how many ends does a cylinder have?

Answer 5

Can you just show me? because this is confusing... && 2? Oh, okay.

Answer 6

so if we combine 2 half spheres, we get a sphere right?

Answer 7

yeah

Answer 8

we also want the lateral area of the cylinder

Answer 9

Which is 12?

Answer 10

no, height is 12, area needs to be calculated

Answer 11

How do you d that?

Answer 12

so the SA of a sphere is
\[SA = 4 \pi r^2\]

and the SA of the lateral area of the cylinder is
the circumference of the circle times the height
\[SA= 2\pi r h\]

Answer 13

Okay hold on and let me see if i can get it

Answer 14

I have a huge feeling I got it wrong.

Answer 15

What did you get?

Answer 16

dunno, didnt calculate it

Answer 17

also im against giving out answers

although i can check your answer

Answer 18

Well I got it wrong

Answer 19

then try it again

Answer 20

r is 4

SA of sphere will be

64 pi

SA of lateral area will be like

8 pi *12

Answer 21

96 pi

Answer 22

96 + 64 = 160

Answer 23

160 pi

i dont have a calculator

Answer 24

Okay well idk what Im doing wrong... Can we go through a different one?

Answer 25

nope,

i need to get up early tomorrow and go to work

Answer 26

what did you get as the answer?

Answer 27

it says its wrong

Answer 28

i dont care that its wrong, i want to know what you got
sheesh

Answer 29

No need to be rude about it

Answer 30

because if i got the same answer as you, that would mean i did something wrong as well

Answer 31

well?, you answer was?

Answer 32

50.24

Answer 33

502.4

Answer 34

huh, i got the same answer

Answer 35

@jim_thompson5910 can you double check my explanation?

Answer 36

you basically have 2 hemi-spherical caps....which combine to a full sphere

so you use 4pi*r^2 to find the surface area of that

then you add that onto the lateral surface area of a cylinder which is 2*pi*r*h

Answer 37

4pi*r^2 + 2*pi*r*h

pi*(4*4^2 + 2*4*12)

160pi

Answer 38

if you want the approximation of this, then

160pi = 502.654824574367 roughly

Answer 39

well something is wrong then, because thats not the answer on here

Answer 40

what are your answer choices?

Answer 41

There is none. so I skipped it.

Answer 42

hmm well maybe they wanted it rounded a different way

Answer 43

Idk, but it was just making me mad. so Im on the next problem
which I still dont get

Answer 44

or...maybe they wanted you to use 3.14 for pi or 22/7 for pi

Answer 45

idk