## Tuesday, April 15, 2008

### Romulo's BOB

What I've Learned About Rectangular Prisms/Cubes

What a Rectangular Prism Is

A rectangular prism is a 3D(Three Dimensional)object that has sides called Height, Length, Width and it looks something like the picture below.

A rectangular prism has 6 faces and those faces are called Top, Bottom, Front, Back, Left Side and Right Side. We can see all 6 faces when we make a diagram called the Net. The Net is just a diagram showing what the rectangular prism would look like if you opened it up and flattened it out. The Net on the left shows all 6 faces and which ones they are and the Net on the right shows what each side is(Height,Length,Width). The Net helps you find the surface area of the prism.

What a Cube is

A cube is basically the same thing as a rectangular prism but the Height, Length and Width are all equal.

Just like the rectangular prism the cube also has 6 faces. The nets are also similar but the only difference is the sides in the cube are all equal. The net of the cube also helps you find the surface area.

How To Find The Surface Area of a Rectangular Prism/Cube

One way of finding the surface area is to divide them into groups and find their areas separately then add them all together. The groups you divide them into are Front/Back, Top/Bottom and Sides(L Side and R Side) because they are both equal and it makes life easier. There are different formulas for each group.

The formula for finding Front/Back is
Area=2(Height X Length) or A=2(H X L)

The formula for finding Top/Bottom is
Area= 2(Width X Length) or A=2 (W X L)

The formula for finding Sides is
Area= 2(Width X Height) or A=2 (W X H)

The 2 is there because after you're done answereing the brackets you multiply what you got in the brackets by 2.
After you find those you add them all up to get the surface area.

The other way to find surface area is to add all the sides up, but that way takes too long.

How To Find The Volume of a Rectangular Prism/Cube

To find the volume you can use the formula Length X Width X Height. The formula says it all so i don't think I need to explain it.

The other formula is Base X Height. The Base is usually either the Top or Bottom. This formula is also simple so I won't explain it.

Solving The Surface Area and the Volume of a Rectangular Prism/Cube