Jamie made a wax model of a rolling pin of diameter 8 cm. The rolling pin was shaped like a right circular cylinder with a right circular cone at each end as shown below.

What was the total surface area of the rolling pin? Using complete sentences, describe the steps you used to calculate the surface area.

Question

Jamie made a wax model of a rolling pin of diameter 8 cm. The rolling pin was shaped like a right circular cylinder with a right circular cone at each end as shown below. 

 

What was the total surface area of the rolling pin? Using complete sentences, describe the steps you used to calculate the surface area.

aravindg · Answer

as shown beow. where is the figure?

aravindg · Answer

*below

anonymous · Answer

ooops sorry XD

aravindg · Answer

so we need to find 3 areas and add

anonymous · Answer

Yes :] I'm not confident about this :<

aravindg · Answer

I will help.first calculate surface area of cylinder.

anonymous · Answer

Cylinder: 2(pi)(r)(h)+ 2(pi)r^2 right?

anonymous · Answer

That's what I learned

aravindg · Answer

yep right

aravindg · Answer

but look closely in that fig we dont need the 2pir^2

aravindg · Answer

the cones covers that surface

anonymous · Answer

Ooooo yeaaa! Haha I feel stupid

aravindg · Answer

no you shouldnt .It just takes some practise

anonymous · Answer

Cone = pi(r)/ 

/ = slant height

aravindg · Answer

surface area=pi r s here

anonymous · Answer

is 12 the diameter?

anonymous · Answer

I'm trying to solve for the cylinder

aravindg · Answer

nope diameter is 8 for both cylinder and cone

anonymous · Answer

Ooooo, I was just making sure. Thank you so much. I'll be back to confirm things XD

aravindg · Answer

ok :)

anonymous · Answer

Wait... if I found the SA of the cylinder and the cones, do I add them t find the actual total of the thing?

aravindg · Answer

yep

anonymous · Answer

I think I did something wrong. Please correct me T_T

I got 2 answers. 427.04 and 458.67

aravindg · Answer

how??

anonymous · Answer

r = 4 because you said the diameter is 8 
so for H, would I substitute 12?

anonymous · Answer

I'm really confused. XD My classmates are, too.

aravindg · Answer

r=4 is true because diameter =8 
h=12 yes

anonymous · Answer

I got 301.59 for the cylinder

aravindg · Answer

ok!

aravindg · Answer

now add 2 cone areas

anonymous · Answer

SO I got the cylinder SA right?

aravindg · Answer

ya

anonymous · Answer

COne = 125.66 

x 2 = 251.32

anonymous · Answer

so 552.91?


or am I wrong? haha

aravindg · Answer

125.66

anonymous · Answer

Aww. The system magically decided to re-set my exam. Which means new set of questions *cries* thanks for helping :)

aravindg · Answer

oh you are welcome !good luck on the new set

aravindg · Answer

btw WELCOME TO OPENSTUDY!

anonymous · Answer

Thank you ^^You'll be my first friend XD

aravindg · Answer

wow thanks :D