OpenStudy (highschoolmom2010):

find the surface are of the cylinders

4 years ago
OpenStudy (highschoolmom2010):

\[SA=2\pi rh+2\pi r^2\] or

4 years ago
OpenStudy (highschoolmom2010):

\[SA=LA+2B\]

4 years ago
hartnn (hartnn):

formula is correct

4 years ago
OpenStudy (highschoolmom2010):

problem is im not sure how to do it

4 years ago
hartnn (hartnn):

you have formula, you have values 17. r=2, h=8

4 years ago
hartnn (hartnn):

in 19th, i think that 7in is the diameter given, you need to find the radius from it

4 years ago
OpenStudy (highschoolmom2010):

\[LA=2 \pi (2*8)\]\[LA=2 \pi (16)\]

4 years ago
hartnn (hartnn):

yes

4 years ago
OpenStudy (highschoolmom2010):

ok so what do i do now that i have that part

4 years ago
hartnn (hartnn):

SA=2πrh+2πr^2 you got 2πrh = 32pi find 2πr^2

4 years ago
OpenStudy (highschoolmom2010):

\[2\pi 9\] \[18\pi\]

4 years ago
hartnn (hartnn):

why did u take r=3 ? :O

4 years ago
OpenStudy (highschoolmom2010):

lol i meant t ill fix it

4 years ago
OpenStudy (highschoolmom2010):

\[2 \pi 4\] \[8\pi\]

4 years ago
hartnn (hartnn):

yesss

4 years ago
OpenStudy (highschoolmom2010):

so now \[32\pi+8\pi=40\pi\]

4 years ago
hartnn (hartnn):

thats absolutely correct for 17th

4 years ago
OpenStudy (highschoolmom2010):

125.663706144 SA=125.7

4 years ago
OpenStudy (highschoolmom2010):

wait i didnt have to do the last part

4 years ago
hartnn (hartnn):

125.7 is approximate answer, only if the answer is not acceptable in terms of pi

4 years ago
OpenStudy (highschoolmom2010):

\[[SA=2\pi (3.5*11)+2(3.5^2)\]

4 years ago
OpenStudy (highschoolmom2010):

it said keep in terms of pi

4 years ago
hartnn (hartnn):

then 40pi is correct and yes, for 19th thats correct too, just simplify

4 years ago
OpenStudy (highschoolmom2010):

\[SA=2\pi (38.5)+2\pi (12.25)\]

4 years ago
OpenStudy (highschoolmom2010):

this is where im confused what to do

4 years ago
hartnn (hartnn):

2(38.5+12.25) = 101.5

4 years ago
OpenStudy (highschoolmom2010):

so \[SA=101.5\pi\]

4 years ago
hartnn (hartnn):

yesss

4 years ago
OpenStudy (highschoolmom2010):

ah thanks again @hartnn for helping :D

4 years ago
hartnn (hartnn):

welcome ^_^

4 years ago