Question

Harry has two similar cans, as shown below.

Can A is a cylinder having radius 2 inches. Can B is a similar cylinder having radius 4 inches and height 6 inches

The lateral area of Can A is ____ square inches. Use π = 3.14

Answer 1

@anikhalder

Answer 2

@Muddingirl ..first lets break up the problem into parts..what do you think ..what's the meaning of similar cans?

Answer 3

the aren't the same size or have the same measurements but they are proportional shapes?

Answer 4

@anikhalder

Answer 5

Exactly..Take a look at the figure
http://assets.openstudy.com/updates/attachments/4fc68193e4b022f1e12e07ac-answerthisnow-1338409386049-help.png

Answer 6

so 2 is half than 4
so half of 6 is 3?

Answer 7

By similar..we can say that the ratio of the radius of the cans will be equal to the ratio of the heights of the cans..:)
Yep...Excellent!
Then height of smaller can is 3..:)

Answer 8

makes sense @anikhalder

Answer 9

Now do we know the formula for lateral surface area of a cylinder?
@Muddingirl

Answer 10

ok that is \[2pir^2h\]

Answer 11

@anikhalder

Answer 12

umm...lateral surface area
think it like this...
first find the circumference of the circular shape of the cylinder at the top and then multiply it by the length..to get the total lateral surface area
2* pi * r * l =lateral surf area..now we can calculate it easily..can't we?
@Muddingirl ..finish up the task..:)

Answer 13

i dont remember how to find the circumference?

Answer 14

to find circumference of any circle the formula is 2*pi*r
And to find the lateral surface area of a cylinder the formula is 2*pi*r*l
(Its like the cylinder is composed of l such circles of circumference 2*pi*r)

Answer 15

okay i do my best

Answer 16

l is the height..you can take it as..2*pi*r*h..instead of 2*pi*r*l...:)

Answer 17

ok

Answer 18

i don't know but for the smallest cylinder i got 37.68 and for the bigger one i got 150.72 i think i did them both wrong

Answer 19

@anikhalder

Answer 20

Both your answers are absolutely correct..:)
#Applause#

Answer 21

oh sweet!! so i only need 37.68 though but THANKS SO MUCH!! @anikhalder i have one more but it'll probably be easy for you

Answer 22

Hey not at all..it's not easy..it's just practice..I am sure you'll be doing them with 5 secs with practice..I make many mistakes...:)
@Muddingirl

Answer 23

oh i hope so i put it in another question @anikhalder

Answer 24

okay..:) I'll try my best