Shape and Space

Hello everyone!

My question is very simple, to the mass majority of users here. But it's important for me as I am retaking my G.C.S.E's. So here goes:

Shape and Space

Could someone help me understand 2-D and 3-D objects i.e everything about them! or even how to understand questions about them when asked in tests and exams.

Would really appreciate your help and advice.

Best of Wishes.

Reply 1

ttoby

That is a very broad topic. This forum is more suitable for taking specific questions so if there are any questions (or even types of questions) that you find particularly hard then feel free to post them here and we can help explain them.

But if you're not understanding any of this topic then your best bet is to get a textbook, start off by answering easier questions then once you've got the hang of them move on to harder questions.

But yeah, if there are any specific things that are difficult then please do post them. Many people on this forum are doing A-levels or above so there'll be plenty of people available to answer your questions.

If you're not sure what exactly you have to know for the exam then either get a text book designed specifically for your exam board or look up the specification document for GCSE maths on the exam board's website. Then you'll know which questions to cover and which topics you don't need to cover.

Reply 2

Lymer

Thank you ^

I think that would be a good start I will post again tommorow as it's quite late now. You've been very helpful, thanks again!

Reply 3

Lymer

Hello Everyone :smile:

Could you please help me with my elementry maths level please :biggrin:

The Question is about, rounding numbers up to the nearest Decimal e.g 5.21267. As I was doing my test online, I found it hard to round the numbers up to 2.dp can someone explan this please.

Also you have long additions, they something like this;

123
460
475
685
457
545
558
556
545
etc

And just say in the units column it goes up to 100 or more, which numbers do I carry forward?? And how I tried asking this somewhere else, but didn't understand. Could you please help, it would be very much appreciated!!

Best of wishes

Reply 4

Ricky116

Original post by Lymer

Hello Everyone :smile:

Could you please help me with my elementry maths level please :biggrin:

Rounding up and down is real simple.

If you were asked to round 5.21267 to 2dp, all you need to do is find the 2nd decimal place 5.21 and if the next number is 5 or higher, the 2nd decimal place is 1 higher.

So, 5.21267 rounded to 2dp gives 5.21 as the next number is 2 which isn't higher than 5 so it stays at 5.21.
If you wanted it rounded to 3dp, you'd find 5.212 and the next number is 6 which is higher than 5 so it is rounded to 5.213.

If someone was to ask you the question "Is 5.2 closer to 5.0 or 6.0?"

Think of it this way.
In order for that number to 'get to' 5.0, you would have to subtract 0.2 from it. So you could say the number is 0.2 'away' from 5.
In order for that number to 'get to' 6.0 however, you need to add 0.8 to it.

So it's 0.2 away from 5, and 0.8 away from 6. Therefore, the answer is that it is closer to 5 (in other words, rounding it to the nearest 0 decimal places gives 5).

Decimal places work the same. If the number was 5.21 and you were asked to round it to the nearest 1dp (i.e. is it closer to 5.2 or 5.3?) you look at how far away the number is from 5.2 and 5.3, and round it to the one nearest.

(edited 13 years ago)

Reply 5

Spungo

I've personally heard of two definitions for dimension though I'm sure there are more.

The first being what most people consider a dimension I imagine, the amount of axis needed to express a shape, object or quantity.
For a line you would just need an axis along the line, with the value determining how far along the axis you go.
For a 2D shape such as a square it would be expressed with 2 axis, usually with one being vertical (y) and one being horizontal (x).
For a 3D shape, you'd need 3 axis. X, Y and Z.

The second definition I've heard of is slightly less intuitive:
Say you have a square. If you enlarge the square by a scale factor of 2, the area of the square increases by 4 times. If you have a cube and you enlarge it by a scale factor of 2, the volume of the cube increases by 8. So the area/volume/size of the shape becomes x^n where x is the scale factor of an enlargement and n is the dimension.

For decimal places:
Rounding is exactly the same as how you would do it for anything else.
I.E for 21.5
Rounding to the nearest 10, you would find the number which 21.8 is closest to.
0, 10, 20, 30 - in this case it's 20
The general rule for rounding a 5 is that you go up.
So 21.5 rounded to the nearest 1 is 22.

In your example: 5.21267
Rounding to 2 decimal places would be rounding to:
5.19, 5.20, 5.21, 5.22, 5.23 etc, which is it closest to?

Reply 6

Lymer

Thank you both :smile:

The answer I see now is 5.21 (as explaned by Ricky116) hehe his explanation was alittle clearer, I've also tumbled on some sites that have explaned alittle more. I just need to practise alittle more. Many thanks for your help brilliant explanations!

Reply 7

Lymer

Hello one and all.

I'm experiancing great difficulty in understanding, conversions between, metric and imperial units. Please could someone shine some light here.

Just something simple, so I can remember it, keep it in my mind, that's easily understandable, if possible. Hope there is a possibility we can do this.

Btw, is there a maths teacher here, that's like easily accessable? so if I have questions, I can email them? would really appreciate this support.

Take care :smile:

Reply 8

Pheylan

Original post by Lymer

is there a maths teacher here, that's like easily accessable?