## Thursday, March 18, 2010

### Alex's surface area growing post

OK, so here are the shapes.
Rectangular Prism

I really do not know how to list the measurements of this rectangular prism but I will try to explain them as best I can.The top front line that is going horizontal is 10 cm, the bottom line on the right side is 15cm, and the line on the front right that is going vertical is 12cm.
Here is the pic or the rectangular prism (above)
Next is the net of a rectangular prism

the measurements of this are the very top line is 10 cm, the bottom line on one of the arms is 15cm, and the side of the arm and head is 12cm.
The formulas for finding the surface are of the rectangular prism are:

Surface area is the sum of the areas of all the faces of a 3-D object.
Surface Area = A1 + A2 + A3 + A4 + A5 + A6,
where A1 represents the area of rectangle 1, A2
represents the area of rectangle 2, etc.

So first I have to find the area:
lxw =a
12x10=a
120=a for a1, a2, a3, and a4
lxw=a
15x12=a
180=a
TSA=120+12o+120+120+180+180
TSA=840

Triangular prism

here is the net

Here is the formula for finding the surface area of the triangular prism and I am solving it here.
Surface area = (3 × area of rectangle) + (2 × area of triangle)
= (1 × 300) + (2 × 120) + (2 x 500)
= 300 + 240 + 1000
= 1540

Cylinder prism

The measurements are the radius of the circles are 5cm, the circumference of the circles are 12cm and the lines are22cm
Here is the net

The measurements are the radius of the circles are 5cm, the bottom line is 12cm and the only vertical lines are 22cm.
The formula's for finding the surface area of a cylinder are
The surface area of a cylinder is the sum of the
areas of its faces.
S.A. = 2 × (π × r2) + (π × d × h) or to shorten this it could be S.A.= 2πr2 + πdh
To solve it I will use the formula
S.A.=2x3.14x25 + 3.14x 10x
And last but not least...my video: