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#1 2015-05-12 03:43:17

shyclaw
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From: Dagoba
Registered: 2015-03-23
Posts: 67

Finding The Surface Area Of A Cylinder

Could someone tell me what this formula for finding surface area means??

A = πr²

Thanks For the help!!!

-Shyclaw ;D


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-Yoda

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#2 2015-05-12 03:48:35

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,974
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Re: Finding The Surface Area Of A Cylinder

This formula gives you the area of a *circle* whose radius is r


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#3 2015-05-12 03:54:02

shyclaw
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From: Dagoba
Registered: 2015-03-23
Posts: 67

Re: Finding The Surface Area Of A Cylinder

Agnishom wrote:

This formula gives you the area of a *circle* whose radius is r


Thank you! ☺

Shyclaw


"“A Jedi uses the Force for knowledge and defense, never for attack.”

-Yoda

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#4 2015-05-12 04:16:14

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,974
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Re: Finding The Surface Area Of A Cylinder

That is not the surface area of a cylinder


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#5 2015-05-12 06:00:36

shyclaw
Member
From: Dagoba
Registered: 2015-03-23
Posts: 67

Re: Finding The Surface Area Of A Cylinder

Agnishom wrote:

That is not the surface area of a cylinder

?


"“A Jedi uses the Force for knowledge and defense, never for attack.”

-Yoda

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#6 2015-05-12 07:48:30

Bob
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Registered: 2010-06-20
Posts: 10,058

Re: Finding The Surface Area Of A Cylinder

If you take a cylinder and "unroll" it you get a rectangle.  The width is equal to the circumference of the top ie. 2 x pi x radius and the height is the height of the cylinder

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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#7 2015-05-15 11:07:38

math9maniac
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From: Tema
Registered: 2015-03-30
Posts: 443

Re: Finding The Surface Area Of A Cylinder

Consider a cylinder with base radius, r and height, h.
The curved surface area of a cylinder = 2(pi)rh
The total surface area of a closed or solid cylinder = 2(pi)r^2 + 2(pi)rh = 2(pi)r (r + h)
This includes the area of the two circular ends.

The total surface area of a hollow cylinder with one end open = pi(r^2) + 2(pi)rh = pi.r(r + 2h)
The total surface area of a hollow cylinder with both ends open = 2(pi)rh

The volume of a cylinder = pi.r^2h


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