## Sunday, March 21, 2010

### Jusitn's Surface Area Growing Post

TSA of rectangular prism

The rectangular prism has rectangular faces.

So, use the formula A = lw to find the area of the faces.

For both the front and back faces, l = 5 in. and w = 2 in.

So, the area of the front and back faces is,

5 2 2 = 20 in.2

For both the top and bottom faces, l = 14 in. and w = 5 in.

So, the area of the top and bottom faces is,

14 5 2 = 140 in.2

For both the sides, l = 14 in. and w = 2 in.

So, the area of the two sides is,

14 2 2 = 56 in.2

Add the area of the faces.

20 + 140 + 56 = 216

So, the total surface area of the given solid is 216 in.2.

TSA of triangular prism

The triangular prism has triangular bases.

So, to find the area of the bases, use the formula:

Substitute 6 for b and 8 for h.

Therefore, the area of the two bases is,

2(24) = 48 cm2

The triangular prism has rectangular sides.

So, use the formula A = lw to find the area of the sides.

The area of the front side is,

13 8 = 104 cm2

The area of the bottom side is,

13 10 = 130 cm2

The area of the back side is,

13 6 = 78 cm2

Find the sum of the base areas and the area of the sides.

48 + 104 + 130 + 78 = 360

So, the total surface area of the given solid is 360 cm2.

TSA of a cylinder

The radius of the circular base is,

he area of a circle is, A = πr2 where r is the radius.

Replace π with 3.14, r with 2.4.

A (3.14)(2.4)2

A = 18.0864

So, the area of one base is 18.0864 cm2.

The sum of the areas of the two bases is,

18.0864 + 18.0864 = 36.1728 cm2

This video is on how to find the tsa of a cylinder , rectangular prism, and triangular prism. It was created by Warren, Bruce and I.