Friday, March 5, 2010

Alvin's Surface Area Growing Post

This is my growing post
First off my rectangular prism:

This is my Net :

The formula I use to calculate the surface area of a rectangular prism is that first I find the area of all the faces, then I add up all the areas of the 6 faces. Thats how I get the surface area to my rectangular prism.
Now I'm going to solve it:
Top = A = LxW
A =6x2
A = 12 cm2
Side = A = LxW
A = 3x2
A = 6 cm2
Front = A = LxW
A = 6x3
A = 18 cm2
Now since I have the area of the 3 sides the other 3 sides are always equivalent so now I find TSA
TSA = side+side+front+back+top+bottom
TSA= 6+6+18+18+12+12
TSA = 72 cm2

My triangular prism:

Net For Triangular Prism:

To find the surface area for a triangle to me its like the rectangle but you have 5 sides and for the triangle faces you have to divide by 2 becuase its half a square.
Now I'm gonna solve it :
Front : A = LxW divided by 2
A = 5x4 divided by 2
A = 10 cm2
Side : A = LxW
A = 6x10
A = 20 cm2
Bottom : A = LxW
A = 4x10
A = 40 cm2
Now the 2 sides are the same because on this triangle they are equivalent.
Now for the TSA
TSA = side+side+bottom+front+back
TSA = 20+20+40+10+10
TSA = 100 cm2
Cylinder Prism:

Cylinder Prism Net :

To Find the surface area no a cylinder you can find the area of all the sides, but that takes to long for me so I just use a simple formula and then plug in the numbers ( 2 x pi x radius squared + pi x d x h). If you are given a radius then you must find the diameter first, and if your given a diameter you must find the radius.
First I'm gonna find the radius because I'm given the diameter.
R= diameter divided by 2
R= 4 divided by 2
R= 2cm
Now I'm gonna solve it :
TSA = 2 x pi x radius squared + pi x d x h
TSA = 2 x 3.14 x 4 + 3.14 x 4 x 6
TSA = 100.48 cm squared


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