## Monday, March 1, 2010

### Allysa's Surface Area Growing Post

Our job is to show everything we learned from a cylinder, rectangular, and triangular prism. At the end, we had to add a video about how to calculate the surface area of all 3 shapes.

Rectangular Prism-

The formula for the surface area of the Rectangular Prism: A = l x w
TOP-
A = l x w
A = 20cm x 14cm
A = 280cm2

SIDE-
A = l x w
A = 5cm x 14cm
A = 70cm2

FRONT-
A = l x w
A = 20cm x 5cm
A = 100cm2

TSA = 280+280+70+70+100+100
TSA = 900cm2

Triangular Prism-

The 2 formulas for the surface area of a Triangular Prism:
- A = l x w
- A =
b x h/2

TOP-
A = l x w
A = 12cm x 6cm
A = 72cm2

SIDE-
A = l x w
A = 12cm x 6cm
A = 72cm2

FRONT- A = l x w
A = 12cm x 6cm
A = 72cm2

A = b x h/2
A = 6cm x 8cm/2
A = 48cm/2
A = 24cm2

TSA = 72cm + 72cm + 72cm + 24cm + 24cm
TSA = 264cm2

Cylinder-

The 4 formulas for the surface area of a Cylinder are:
- d/2 = r OR If you have the radius it's, r x 2 = d
- (pi)d = c
- (pi)r2 = area of a circle
- A = l x w (area of a rectangle)

r = d/2
r = 16cm/2
r = 8cm

c = (pi)d
c = 3.14 x 16cm
c = 50.24cm

area of a circle = (pi) x r x r
area of a circle = 3.14 x 8cm x 8cm
area of a circle = 200.96cm2

area of a rectangle = l x w
area of a rectangle = 72cm x 50.24cm
area of a rectangle = 3617.28cm2

TSA = area of a circle + area of a circle + area of a rectangle
TSA = 200.96 + 200.96 + 3617.28
TSA = 4019.2cm2