Maths Genious Required

[Yatesyz]

I don't understand how "surds" work.

 

Here is an example..

 

Simplify :

 

Answer :

- How do you get that?

 

[kingvercetti]

To simplify surds you find two numbers which multiply to make the number if it wasn't a root, in your case, 12 = 4 * 3; one of these numbers has to be a square number, and for simplicities sake pick the biggest square number that goes into it, which in this case is 4. rt4 * rt3 = rt12; the square root of 4 is 2, therefore rt12 = 2rt3.

 

rt = square root btw, I can't be arsed to go and dig up the symbol in character map.

 

Another example is rt32, the biggest square number that goes into 32 is 16;

32 / 16 = 2, so

rt32 = rt16 * rt2,

root 16 is 4 (4 * 4 = 16),

so rt32 = 4rt2.

Edited May 18, 2008 by kingvercetti

[Yatesyz]

To simplify surds you find two numbers which multiply to make the number if it wasn't a root, in your case, 12 = 4 * 3; one of these numbers has to be a square number, and for simplicities sake pick the biggest square number that goes into it, which in this case is 4. rt4 * rt3 = rt12; the square root of 4 is 2, therefore rt12 = 2rt3.

I think I understand a bit better now. Thanks.

[kingvercetti]

I added another example to my previous post just to try and make it a bit clearer mate.

[Yatesyz]

I added another example to my previous post just to try and make it a bit clearer mate.

I'm pretty sure I understand it now. Thanks again.

 

Could you possibly explain this more tricky one?

 

[Venom]

 

rt8 / rt6

 

rt2.rt4 / rt2.rt3

 

rt4 / rt3

 

2 / rt3

[Yatesyz]

rt8 / rt6

 

rt2.rt4 / rt2.rt3

 

rt4 / rt3

 

2 / rt3

On the calculator I get 2rt3 / 3.

[Venom]

rt8 / rt6

 

rt2.rt4 / rt2.rt3

 

rt4 / rt3

 

2 / rt3

On the calculator I get 2rt3 / 3.

Same thing.

 

Check their decimal value. Should be the same.

[Yatesyz]

rt8 / rt6

 

rt2.rt4 / rt2.rt3

 

rt4 / rt3

 

2 / rt3

On the calculator I get 2rt3 / 3.

Same thing.

 

Check their decimal value. Should be the same.

Oh yeah. Thanks.

[TenaciousD.]

Does someone have a maths GCSE exam tommorow? I know I do.

 

Anyway, I took this of my maths revision guide. Hope it helps you.

 

El Clicko.

[Yatesyz]

Does someone have a maths GCSE exam tommorow? I know I do.

 

Anyway, I took this of my maths revision guide. Hope it helps you.

 

El Clicko.

Yeah I do.

 

I really haven't revised as much as I should have done.

[Dodgy Dan]

I had my A level maths exam a few days ago (which I failed extremely). Was f*cking impossible. You should feel lucky

 

But yeh looks like kv explained it pretty well, basically you find the biggest squared number in the surd and then square root that leaving what its multiplied by inside the square root.

[radicell]

What does "surds" mean? In my school these are called "radicals".

[Girish]

What does "surds" mean? In my school these are called "radicals".

The root sign (√) is known as radical and a quantity that uses a radical is called a 'surd'.

[D0c]

f*cking ell mate, Good luck with your exams, got my A2 Mechanics exam next week and me looking back at that GCSE stuff now it's like 2 + 2, if you got more problems ask. My biggest tip go find some EXAM PAST PAPERS and do them, learn the nature of the question and know how you solve them. Don't forget about trigonometry sh*t SOH CAH TOA, which tier are you (higher, itermediate or foundation) I can get you some past papers from our school's web site.

Edited May 18, 2008 by D0c

[Yatesyz]

 

f*cking ell mate, Good luck with your exams, got my A2 Mechanics exam next week and me looking back at that GCSE stuff now it's like 2 + 2, if you got more problems ask. My biggest tip go find some EXAM PAST PAPERS and do them, learn the nature of the question and know how you solve them.  Don't forget about trigonometry sh*t SOH CAH TOA, which tier are you (higher, itermediate or foundation) I can get you some past papers from our school's web site.

Yeah I struggle with SOHCAHTOA. If you could help me with that I would be very happy.

 

EDIT: doing higher paper.

Edited May 18, 2008 by Yatesyz

[mike39]

I'm pretty happy I've remembered how to do this. I wonder what year of school most people learn this in ... I bet that's probably the peak of what I remember from high school math.

 

I made it to Calculus but never finished it.

[BuffaloSoldier]

 

rt8 / rt6

 

rt2.rt4 / rt2.rt3

 

rt4 / rt3

 

2 / rt3

On the calculator I get 2rt3 / 3.

The uncanny rule is that you cannot have radicals in the denominator. They will multiply both numerator and denominator by r3 and that's how you ended up with your answer.

[Robinski]

Lol, guess I'm in the "got a maths GCSE paper tomorow but havent thought about revisinguntil the night before" club. Was a bit odd actually I just came here after looking over the maths revision guide that Ten. D posted a picture of earlier and then i see this topic, a fraction of it was way over my head but i got most of it I think. Anyway, good luckto everyone, will post here tomorow probably with my opinion on it.

[TenaciousD.]

 

f*cking ell mate, Good luck with your exams, got my A2 Mechanics exam next week and me looking back at that GCSE stuff now it's like 2 + 2, if you got more problems ask. My biggest tip go find some EXAM PAST PAPERS and do them, learn the nature of the question and know how you solve them.  Don't forget about trigonometry sh*t SOH CAH TOA, which tier are you (higher, itermediate or foundation) I can get you some past papers from our school's web site.

Yeah I struggle with SOHCAHTOA. If you could help me with that I would be very happy.

 

EDIT: doing higher paper.

Easy way to remember it:

 

Sex On Hard Concrete Always Hurts The Orgasmic Area.

 

Edited May 18, 2008 by TenaciousD.

[Yatesyz]

f*cking ell mate, Good luck with your exams, got my A2 Mechanics exam next week and me looking back at that GCSE stuff now it's like 2 + 2, if you got more problems ask. My biggest tip go find some EXAM PAST PAPERS and do them, learn the nature of the question and know how you solve them.  Don't forget about trigonometry sh*t SOH CAH TOA, which tier are you (higher, itermediate or foundation) I can get you some past papers from our school's web site.

Yeah I struggle with SOHCAHTOA. If you could help me with that I would be very happy.

 

EDIT: doing higher paper.

Easy way to remember it:

 

Sex On Hard Concrete Always Hurts The Orgasmic Area.

Haha, I can remember it but I don't know how to use it.

[Yatesyz]

Another question.

 

How do I know wether to use sin, cos or tan on this?

[TenaciousD.]

First you need to find which side is which (Opp, Hyp or Adj) then apply the one which fits.

 

Imagine the angle is a speaker, and music is blasting out, the music would hit the Opposite angle because it is opposite the angle.

The Hyp is always the longest angle and the Adj is the last one.

 

Then you apply SOHCAHTOA.

 

SOH, CAH, TOA

 

The middle letter goes ontop to form a pyramid, so it is O above S and H, A above C and H and O above T and A.

 

Then you pick which triangle is needed, so SOH has Opp and Hyp and so on...

[Yatesyz]

 

First you need to find which side is which (Opp, Hyp or Adj) then apply the one which fits.

 

Imagine the angle is a speaker, and music is blasting out, the music would hit the Opposite angle because it is opposite the angle.

The Hyp is always the longest angle and the Adj is the last one.

 

Then you apply SOHCAHTOA.

 

SOH, CAH, TOA

 

The middle letter goes ontop to form a pyramid, so it is O above S and H, A above C and H and O above T and A.

 

Then you pick which triangle is needed, so SOH has Opp and Hyp and so on...

So you always use the one opposite the angle and the one where the length is given, not where the x is?

[D0c]

for that triangle you would use CAH because you know the Hypotenuse (the longest side) and you need the side that is attached to the angle called adjecent so you have A and H therefore you use CAH. This means that cos 43 = x / 8 and then you just rearange to get x so it'll be x = 8 cos 43

 

 

Listen i've found the past papers they're from Edexcel though, is that the ones you are doing cause i could you send you them or upload them somewhere.

Edited May 18, 2008 by D0c

[Effy in Chains]

God damn geniuses and your god damn learned maths.

[Yatesyz]

for that triangle you would use CAH because you know the Hypotenuse (the longest side) and you need the side that is attached to the angle called adjecent so you have A and H therefore you use CAH. This means that cos 43 = x / 8 and then you just rearange to get x so it'll be x = 8 cos 43

So you always use the side where the length is given (hypotenuse on this triangle) and the side which you're trying to find out (x)?

[TenaciousD.]

for that triangle you would use CAH because you know the Hypotenuse (the longest side) and you need the side that is attached to the angle called adjecent so you have A and H therefore you use CAH. This means that cos 43 = x / 8 and then you just rearange to get x so it'll be  x = 8 cos 43

So you always use the side where the length is given (hypotenuse on this triangle) and the side which you're trying to find out (x)?

yeah, you just change the formula triangle for whatever the question is.

[Yatesyz]

Still having problems, stuck on this one.

 

 

[dills]

 

Still having problems, stuck on this one.

 

 

Well, the sides that are involved are the opposite and hypotenuse sides, that means that sin will be used (SOHCAHTOA).

 

So type sin 17 into the calculator and that gives 0.29273.......

 

That means 0.29273 = 42.3 (opposite) / X (hypotenuse)

 

Multiply both sides by X to give, 0.29273X = 42.3

 

Divide both sides by the 0.29273 to find out what 1 X equals and that gives a length of 144.7 for X (hypotenuse).

 

 

 

To test that is the right answer, you can do 42.3 / 144.7 and then do the inverse of sin for the value that you get. So sin-1 of (42.3 / 144.7) = 17.