Question

help!
Anita made a wax model of a rolling pin of diameter 6 cm. The rolling pin was shaped like a right circular cylinder with a right circular cone at each end as shown below.
A rolling pin shaped as a cylinder with conical ends. The length of the cylindrical part is 9 cm, the slant height of each cone is 4 cm and the diameter of the rolling pin is 6 cm.
http://learn.flvs.net/webdav/assessment_images/educator_geometry_v14/pool_Geom_3641_0810_19/image0014e68d166.jpg
What was the total surface area of the rolling pin? write out steps please

Answer 1

url requires login, try with a screenshot instead

Answer 2

surface area of the cylinder (without its bases) : 2*pi*r*h
surface area of each of the cones (without base) : pi*r*s (s=slant height)

can you do it now ?

Answer 3

here it is

Answer 4

@jdoe0001

Answer 5

it is ok.. look at what i wrote .. the text was informative we dont really need the picture

Answer 6

so the surface area of the cylinder would be 169.56 and the surface area of the cone is 37.68 but now what do i do to find the total surface area to i add them together?

Answer 7

well first notice that we ignore the bases since the base of each cones touches a different base of the cylinder

Answer 8

now, we have 1 cylinder and 2 cones .. so what we should do ?

Answer 9

ummm would you subtract the base from each one?

Answer 10

now as you can see the formulas that i wrote are formulas for surface areas WITHOUT bases

Answer 11

so no worries about the bases anymore. i just wanted to point it out

Answer 12

you wrote
"so the surface area of the cylinder would be 169.56 and the surface area of the cone is 37.68 but now what do i do to find the total surface area to i add them together?"

now we have
surface area of the cylinder (without bases) : 169.56
and surface area of one cone (without base) : 37.68

we have 1 cylinder and 2 cones .. what we should do then ?

Answer 13

add them together

Answer 14

169.56 + 37.68 ? what about the second cone ?

Answer 15

add 37.68 to it again

Answer 16

correct

Answer 17

to make it 169.56+37.68+37.68= 244.92?

Answer 18

yes

Answer 19

now just one moment..
what if you had only one cone ?

Answer 20

then it would be 207.24

Answer 21

no, since we need to add one base (you see the left base is part of the surface now!)

Answer 22

when we had two cones, no one of the bases (nor the cylinder and not the cones) were part of the surface of the shape
now, we have one base that is part of the surface of the shape

Answer 23

sorry for my English by the way

Answer 24

so would you add 6 to it because that is the diameter of it?

Answer 25

no, the area of one base of the cylinder (which is in fact area of a circle ) = pi*r^2

Answer 26

so would you add 28.26 to it?

Answer 27

yes