Question

Sara made a wax model of a rolling pin of diameter 10 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 14 cm, the slant height of each cone is 6 cm and the diameter of the rolling pin is 10 cm.

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

Answer 1

Okay just know the equations for the surface area
1) The cone, the surface area of it is : \[\pi r l\]

2) then the cylinder, curved surface area is :\[2 \pi r H \]

Answer 2

ok so what do i do im so confused!

Answer 3

its surface area of the open cylinder plus 2 x the surface are of the cones

Open Cylinder

\[SA = 2\times \pi \times r \times h \] r radius h = height

Cone

\[SA = \pi \times r \times s\] r = radius s = slant height

Answer 4

well okay, u know the values...always remember its better to sought them out first...and then add them altogether..Follow me!

For the cone:\[\pi r l\]
\[\pi \times 10 \times \]

u get the surface area of cone, you have to multiply by two, so that u get two cones on either end...

Coming to the culinder u know the equation, \[2 \pi r H\]
\[2 \times \pi \times 10 \times 14\]
get the values and add...u ge tthe total sufrace area

Answer 5

\[\pi r l----l --\]
is the slant height which is 6 cm

Answer 6

so the diameter is 10 cm so the radius is 5 cm

the total surface area is

\[SA = 2 \times \pi \times 5 \times 14 + 2( \pi \times 5 \times 6) = 200 \pi\]

Answer 7

i think @campbell_st has a better solution for this..

Answer 8

thanks @thushananth01 and @campbell_st <3