The Geometry of Three Dimensions: Surface area of a prism

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Lexcy585

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i have to find the suface area of a rectangular solid whose dimensions are: 15in., 10.0in., and 2.0ft. How would i figure this problem out when the units aren't the same? Would my answer be in inches or feet?

Thanks !
 
Lexcy585 said:
i have to find the suface area of a rectangular solid whose dimensions are: 15in., 10.0in., and 2.0ft. How would i figure this problem out when the units aren't the same? Would my answer be in inches or feet?

Thanks !
Click to expand...

Your answer could be in either SQUARE inches, or in SQUARE feet. But, you need to convert all of the dimensions to one or the other...either inches, which would be 15 in, 10.0 in and 24.0 in, OR in feet, which would be (15/12) feet, (10.0/12) feet, and 2.0 feet.

Then, find the areas of each of the rectangular faces, and add them up to get the total surface area.
 
I know you gave me the conversions but what method would i use to convert it? Additionally, on my next problem, it's centimeters and meters, so would i use the same method to convert it to centimeters?

Thanks !
 
Lexcy585 said:
I know you gave me the conversions but what method would i use to convert it? Additionally, on my next problem, it's centimeters and meters, so would i use the same method to convert it to centimeters?

Thanks !
Click to expand...

I guess you are expected to KNOW the basic relationships between units of length, such as

1 foot = 12 inches
1 yard = 3 feet
etc......

There are lots of tables of weights and measures available online or in your math text, I'd assume.

If you are dealing with centimeters and meters, you would need to know the relationships between the metric units of length.

1 meter = 100 cm
1 km = 1000 m
etc....
 
my daughter needs help with a few math problems if anyone can help

What polygon has 9 diagonals?
 
ok thanks so much ! Algebra is somewhat of a blurr ever since i started geometry!
 
affordablecab said:
What polygon has 9 diagonals?
Click to expand...

Let d denote the number of diagonals and n the number of vertices. Then d is calculated for a convex polygon by:

d=n(n−3)2\displaystyle \displaystyle{d=\frac{n(n-3)}2}

Plug in d = 9 and determine n.

I've got n = 6. That means a hexagon has 9 diagonals.
 
The Geometry of Three Dimensions: Volume of a Prism

The area of the base of a prism is 48 square feet and the height is 18 inches. Can someone please help me figure this out ?
Thanks!
 
Lexcy585 said:
The area of the base of a prism is 48 square feet and the height is 18 inches. Can someone please help me figure this out ?
Thanks!
Click to expand...

1. The volume of a prism is calcvulated by:

V=(base area)⋅(height)\displaystyle V = (base\ area) \cdot (height)

2. First you have to convert the measure of the height from inches to feet:

18′′=1.5′\displaystyle 18'' = 1.5'

3. Now plug in this value into the equation at #1. Keep in mind that the result will be in cubic feet!

By the way: Please start a new thread if you have a new question. Otherwise you'll risk that nobody will notice that you are in need of some support.
 
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