## Thursday, February 25, 2010

### Ralph's Surface Area Growing Post

Rectangular Prism:

To find the area of a square you use this formula

a= lxw

Using this formula I can find the area of a rectangular prism. First I have to make a net of the rectangular prism then I use the formular for each face on the prism. After I find the area of all the faces I add them all up to get the Total Surface Area.

TSA=50+50+30+30+15+15

TSA=190cm(2)

Triangular Prism:

To find the area of a triangle you use this formula

a=lxw/2

Using this formula I can find the area of a triangular prism. First I have to make a net of the triangular prism then I use the formular for each face on the prism. I used the rectangular prism formula when there was a square and used the triangular prism formula when there was a triangle. After I find the area of all the faces I add them all up to get the Total Surface Area.

TSA= 1.89+0.98+1.61+1.61+1.61

TSA=7.7cm(2)

Cylinder :

For the cylinder you use 2 formulas.

To find the circumference you use this formula. C = pi x r x r

If you need to find the area of the circle you use: a = (pi) x d

Using this formula I can find the area of a triangular prism. First I have to make a net of the cylinder. Next I used another formula to get the diameter of the cyclinder (which would be r x 2 = d). After that I used the radius to calculate the circumference. Next I used the diamter to find the area of the circle. Next I used the rectangular prism formula to figure out the rectangular part of the net. Finally I added the 2 circles and the rectangular part of the net and got the TSA.

TSA=314+314+1381.6

TSA=2009.6

How to find the TSA of a cylinder

How to find the TSA of a trianglar prism:

How to find the TSA of a rectangular prism: