## Wednesday, March 3, 2010

### Brendan's Surface Area Growing Post

To find the surface area of a rectangular prism, you must use the formula "A=L x W" to find the surface area of a face of the rectangular prism.
I found the surface area of my rectangular prism by finding the surface areas of all six faces and adding them all together.

a=L x W a=5x10 a=50 squared cm
a=8x10 a=80 squared cm
a=8x5 a=40 squared cm
a=5x10 a=50 squared cm
a=8x10 a=80 squared cm
a=8x5 a=40 squared cm

TSA=50+50+80+80+40+40

TSA=240 squared cm

To find the surface area of a triangular prism, you must use the formula "A=L x W/2" for the triangle faces and "A=LxW" for the rectangle faces.
I found the surface area of my triangular prism by finding the surface areas of all five faces of the triangular prism and adding them all together.

a=L x W a=3x3 a=9 squared m

a=3x4 a= 12 squared m

a=5x3 a=15 squared m

a=L x W/2 a= 4x4/2 a=8 squared m

TSA= 9+12+15+8+8
TSA= 52 squared m

To find the surface area of a cylinder, you must use the formula "A=2 x pi x rsquared + pi x d x h" or "A=pi x r x r" to find the circles surface area and "A=l x w" for the big rectangles surface area. Then you can add the two circles surface area and the big rectangles surface area to get the total surface area.
I found the surface area of my cylinder by finding the area of the two cirlces and the big rectangle.

r=d/2 r=5/2 r=4.5 squared mm

C=pi x d C= 3.14 x 5 C= 15.7 mm

a=pi x r x r a= 3.14 x 4.5 x 4.5 a= 63.59 squared mm

a= L x W a=15.7x10 a=157

TSA= 63.59+63.59+157
TSA= 284.18 m