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??????
 
I'm pretty good up to pre-calc after that a bit useless.
 
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.
 
1.2 bits of pie? That's not very much.

:D
 
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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