# Homework Help: Geometry 3

1. Jun 15, 2010

### thereddevils

1. The problem statement, all variables and given/known data

The diagram shows a box that has six faces .The top and bottom faces are square . THe other faces are all identical. What is the volume of the box ?

2. Relevant equations

3. The attempt at a solution

#### Attached Files:

• ###### geometry 333.jpg
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2. Jun 15, 2010

### Axiom17

What's your attempt so far? I.e. method and calculations?

3. Jun 15, 2010

### njama

Hint: It is Pyramidal Frustum. Correct me if I am wrong.

4. Jun 15, 2010

### Axiom17

No that's what I was thinking too cheers njama on posting the link

OK, so thereddevils give that a go now!

5. Jun 16, 2010

### thereddevils

ok so from the formula for volume of a pyramidal frustum is given by

V=1/3(A1 + A2 + root(A1)(A2))(h)

the height is root(18)

A1=100 , A2=16

i got V=220 cm^3

but the answer given is 312 cm^3.

6. Jun 16, 2010

### rl.bhat

According to the diagram h = 6 cm.

7. Jun 16, 2010

### Axiom17

Yes the formula is:

$$V=\frac{1}{3}h \left( A_{1}+A_{2}+\sqrt{A_{1}\times A_{2}} \right)$$

Where $A_{1}$ is the bottom area, $A_{2}$ is the top area, and $h$ is the height. Refer to your diagram for these values.

If you check that you're using all of the correct values , then you'll get the answer.