Calling all maths geniouses or whatever the plural is!

Kev M

Kev M

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I'm stuck, I've decided to do a distance learning HNC in mechanical enginering, I've got a maths question and I don't even understand what it's asking. I've done lots of working out and have lots of answers but I have no idea WTF they are looking for and I can't get hold of a tutor.


HEEEELLLLP!:bang:
 
somnething more to go on might help so we can tell if we can be of any use??????
 
We don't know whether we're genius' until we see how bad the question is Kevin ... give us a clue ... :shrug:

I am sure someone here will be able to give you guidance ... however bad it is ... :thinking:





:p
 
I did HNC electronics many many years ago. I remember starting the course thinking it would be mainly about electronics. Turned out to be mainly about maths. Have to admit I gave up on trying to understand it all and concentrated on learning how to get the answers - I passed :)
 
Sounds like a plan robert, right then I'm not after the answers as I've got a load in front of me I just don't get what the question is looking for so here it is (I've substituted certain greek letters for keyboard symbols).

Given that x=3sin@ and y=4cos@, express x+y in the form Rsin(@+$) giving $ in radians correct to 4 decimal places and hence solve the equation,

3sin@ +4cos@ =1.2

giving your answers in radians in the range -pie to +pie (anyone says mmmm pie and I will hunt you down)

I've got the Rsin(@+$) bit right I think but I'm not sure how it solves the

3sin@+4cos@=1.2 bit.
 
Maths! not a scooby do!

mmmpiaa4.jpg
 
You have my deepest sympathies - I hated that stuff nearly as much as calculus.

mmmm.... no maybe not ;)
 
I think I've got to work out what the values of @ are and express them in radians for all values between -pie and +pie. I think.
 
If 3sin@ + 4cos@ = Rsin(@+$)

then

4cos@ = Rsin(@+$)-3sin@

then

3sin@ +(Rsin(@+$)-3sin@) =1.2

Then Rsin(@+$)=1.2

Although seems too straightforward!

Or you could ask an A level student - I've forgotten more than I knew
 
I just love reading threads like this cos I havent a bloody clue what its all about.:lol:






Mmmmm... Stick to driving lorries for a living.:razz:
 
I would have done what Darkstar did but I'm also not sure that is what they are after. University maths was a long long time ago.... I now use the other side of my brain for a living.
 
I did HNC applied physics but it was the maths I enjoyed - but that was close to 30 years ago and I'm veeeeeery rusty!!!!
 
Can;t remember how to do them Kev. :'( but i'm looking...

Can however recommend 3 books i used to do a degree in Information Technology with Psychology - this meant doing a degree in maths.

Engineering Mathematics and Further Engineering Mathematics - by K A Stroud

and another by J O Bird - think it was called engineering maths - can't see it on my bookshelf at the mo.


In terms of the question aren't you trying to rearrange the formula so that you have @=.... whatever is gets to lots of cos and sins - might be totally off here - but think you have to use the power of sin's and cos's eg http://www.mth.uea.ac.uk/jtm/12/Lec12p7.pdf
 
Kev Mills said:
Sounds like a plan robert, right then I'm not after the answers as I've got a load in front of me I just don't get what the question is looking for so here it is (I've substituted certain greek letters for keyboard symbols).

Given that x=3sin@ and y=4cos@, express x+y in the form Rsin(@+$) giving $ in radians correct to 4 decimal places and hence solve the equation,

3sin@ +4cos@ =1.2

giving your answers in radians in the range -pie to +pie (anyone says mmmm pie and I will hunt you down)

I've got the Rsin(@+$) bit right I think but I'm not sure how it solves the

3sin@+4cos@=1.2 bit.
Click to expand...

:tumbleweed:
 
I just love reading threads like this cos I havent a bloody clue what its all about.
Click to expand...

Me either, I just came in to see who all the really clever people are. :lol:
 
Urghh makes hed hurt.. not had to do this since Uni

OK...

[:geek: Mode on]

This is a vector rotation problem....

Rsin(@ + $) = sin(@)cos($) + sin($)cos(@)

That from memory (and a web crib) is the ingredient you are missing...


And it's PI not PIe (although the latter does allow lots of scope for humour... :))

Now you have that it should be possible to work out what $ is.
I can't though since I'm off to bed now

[:geek: Mode off]


Yum I like...
cc444-apple-blackberry-pie-18775.jpg
 
Thanks for you help I have some answers so they're all going in and I'm hoping one of them is what they're looking for.

R=5
$=53.1301deg or 0.9273rad
@=0.6849rad and1.9719rad
 
I got it thanks Keltic. Turns out that question was the easy starter for ten. I won't bother you all with the rest fo them.

Kev
 
You'll probably never use any of that in the real world.
I did my ONC (OTC) and HNC (HTC) about 20 years ago and don't really remember doing any of that. Never used any of it since that's for sure.
Eaten a few pies though, just not all of 'em.
 
nilagin said:
You'll probably never use any of that in the real world.
I did my ONC (OTC) and HNC (HTC) about 20 years ago and don't really remember doing any of that. Never used any of it since that's for sure.
Eaten a few pies though, just not all of 'em.
Click to expand...

I was about to say the same .... just different Exams and the time scale has increased .... hmmm .... let me see .... 37 years and still not had a real need.... except....

My son's homework and helping out on Fora and the like.... I think only J. Robert Oppenheimer really applied this stuff and that was because he wanted to blow things out of all proportion :lol: (In a Manhattan sort of way)!
 
chuckles said:
I was about to say the same .... just different Exams and the time scale has increased .... hmmm .... let me see .... 37 years and still not had a real need.... except....

My son's homework and helping out on Fora and the like.... I think only J. Robert Oppenheimer really applied this stuff and that was because he wanted to blow things out of all proportion :lol: (In a Manhattan sort of way)!
Click to expand...

Unless you write S/W for real time applications or games.
In which case a solid grasp of vector mathematics is a real bonus

... dohhh I'm at it again... :geek: :bang:
 
So if

3sin@ + 4cos@ = Rsin(@+$)

then

4cos@ = Rsin(@+$)-3sin@

then

3sin@ +(Rsin(@+$)-3sin@) =1.2

Then Rsin(@+$)=1.2.................................but......if the next footy match over runs on ITV, what time will corry start :bonk:
 
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