Cutting Cuboids

[chugbottle]

A sculptor works with large wooden cuboids (rectangular prisms), cuts them into three smaller cuboids and then paints them black, white and grey. The volume of the black cuboid is always twice the volume of the white one and the volume of the white cuboid is always twice the volume of the grey one.

The diagram shows how this works. The cuts are always parallel to the face marked with w and h. We will always denote the surface areas of the separated cuboids by A1 (black) , A2 (white) and A3 (grey).

(see attached doc)

a) The sculptor is given a block for which l = 1, w = 6 and h = 3.
Show that with these values the ratio of A1 to A2 is 3:2

b) Show that for any cuboid the sculptor cuts, A1 is always less than 2A2

c) The sculptor wants a cuboid with h = w, which will give A1 to 3A3 . what would be the value of l in terms of w?

d) The sculptor decides she would like to have A1 to A3 = 4:3. If this is to be the case, find a formula linking l, w and h and give an example of the dimensions of a cuboid, before it is cut, for which this will work.

I need help with (d) above. Thanks.

[am99]

wit a u just gotta show the working out of the Surface Area of the cubiods and show that there is a 3 is to 2 ratio in there Surface Area
these Q are hell hard though
latrs
guys hurry and answer these ay

[enthumath]

Here's a deal:

I give you 3d you give me 5 b of math challenge

lol

Hint to 3d is express a1 and a2 in terms of w ,l and h

I'II give you more clues if you give me 5 b

[chugbottle]

I am stuck with 5 b too.
sorry.........

[enthumath]

The value of l in terms of w is w.

sounds stupid but if you substitute value it will be correct.

[BIG T]

I need help with 3d to and i gtta hand it in tomorow

[am99]

yea umm ok lol wats going on?
i kno ppl with the answer
but we got told today that we need to explain how we get it lol

[enthumath]

Am I right to 3c)

the answer is w

[unknown2006]

can someone help me with 3 b,c,d please

[am99]

**** this is hard man any1 on this post atm?

[markneale]

I don't get what opus says in the previous (closed) thread about cutting cuboids & using search, I can't find anything & am also stuck on part D re 4:3. Need help please.

[Breton]

Man does any1 just have the answer to b,c and d? :mad:

[penagate]

Perhaps you should ask your lecturer/teacher/course instructor for the answers to the questions, and see what they say.

This forum is not for doing people's homework for them. No online forum should be first place you go when you have difficulty with homework. Instead, you should consult your textbook/course notes, try and work it out yourself, and if you still have trouble, talk to a relevant member of the staff at your school/college/university. They won't give you the answers straight up, but they should be able to help you find them.

And like them, we here might be able to help too, but only if you show us that you've made some attempt at the question yourself. Just saying that you're stuck isn't good enough.

This thread has been up for nearly two weeks. A question like this shouldn't take that long to do. If you'd rather just wait until someone takes pity on you and gives you the answers, then you shouldn't be taking the course.

[markneale]

Perhaps you should ask your lecturer/teacher/course instructor for the answers to the questions, and see what they say.

This forum is not for doing people's homework for them. No online forum should be first place you go when you have difficulty with homework. Instead, you should consult your textbook/course notes, try and work it out yourself, and if you still have trouble, talk to a relevant member of the staff at your school/college/university. They won't give you the answers straight up, but they should be able to help you find them.

And like them, we here might be able to help too, but only if you show us that you've made some attempt at the question yourself. Just saying that you're stuck isn't good enough.

This thread has been up for nearly two weeks. A question like this shouldn't take that long to do. If you'd rather just wait until someone takes pity on you and gives you the answers, then you shouldn't be taking the course.

Thanks for the lecture, I have worked hard to almost finish this piece of work & it is only this part of the question that is giving me grief. Teacher has been too busy & then away sick & now have a casual!!!!! As you can see I am new to this & just wanted to know how to do it, but handed it in yesterday incomplete. The fact that this thread is 2 weeks old & not answered makes me wonder?????????????????????????????????????????????

[kleinma]

makes you wonder what?

The math forum on this website gets VERY little traffic compared to the main VB programming sections of this site...

So there is generally only a handful of people who have even come across this post, let alone provide an answer to it.

[markneale]

makes you wonder what?

The math forum on this website gets VERY little traffic compared to the main VB programming sections of this site...

So there is generally only a handful of people who have even come across this post, let alone provide an answer to it.

Tell me something I don't know, like the answer to the question!!!

[kleinma]

Tell me something I don't know, like the answer to the question!!!
you must be in his class??

[markneale]

you must be in his class??

Who's class?
You also say not many people view these posts; I see nearly 900 views for this thread??

[M_G_101]

Just a word...well hints you could say...
With 5 b i will tell you something that may end up helping you with understanding the equation 'Isabel' has...
W stands for the number of tiling patterns you can make and the little n is how wide they have to be i.e. W3 is the number of ways you can make tiling patterns that are 3 units wide so W1=1, W2=2, W3=3, W4=5, W5=?
-- Use the formula for W5--
Oh... and MAYBE Fibonacci has something to do with it... ;)
Hope this helps! No doubt it helped me...
P.S. This is exactly the type of hint that a teacher gave me so i am not repeating anything that can't be said...

[M_G_101]

Sorry i didn't realize i repeated what i posted...Soz