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Reply 160
Original post by AK0001
I think I'll do 4 Solomon papers and all of edexcel. I did the edexcel papers back in january, so i'm a bit hazy on it.


Tbf just pick them randomly they're all pretty much at the same level.

Original post by arvin_infinity
Which of the papers did you find hard so far!
To me I think it was jun07


I cried after finishing June 06 :P
Reply 161
Original post by CraziiFreak
Solomon papers are all of the same difficulty level (at least thats what i think) unlike edexcel where some papers are easy while others are hard. So for solomon papers it doesn't really matter which one you do, seeing you don't have enough time, i would say why don't you do alternative? like do paper A solomon then go to paper C, E etc.
Yes definitely need to invest more time on maths. PRACTICE is the key. :smile:

Anyway good luck.


Thank you! Hopefully I'll be okay, need an A in maths :/.
Reply 162
heey, for the R-addition formulas, do we have to know how to prove how we get these? Or do we just need to know how to use them to prove identities and find R and alpha etc, if this makes sense? :smile:
Reply 163
Just a quick question about functions. Why is f(x) = Square root x, a function if domain is x>=0, since it still remains a mapping of one-to-many (for every +/- y there is an x value).

Please reply.
Original post by The_Pen
Just a quick question about functions. Why is f(x) = Square root x, a function if domain is x>=0, since it still remains a mapping of one-to-many (for every +/- y there is an x value).

Please reply.


I'm pretty sure that's wrong. Where did you see this?
Original post by The_Pen
Just a quick question about functions. Why is f(x) = Square root x, a function if domain is x>=0, since it still remains a mapping of one-to-many (for every +/- y there is an x value).

Please reply.


Maybe I am sketching the wrong thing..but if am write that's a function and it's not 1 to many nor its' many to one


Please quote me if you found the right ans.
When proving trig, do you always need to start with the left hand side to prove the right hand side, or can you start from the RHS and work to the LHS? Asking because there are a few which I find easier/quicker to do the other way round.
Reply 167
Original post by knowledgecorruptz
I'm pretty sure that's wrong. Where did you see this?


It's in the Edexcel C3 text book. I agree that it's wrong because +square root x would be a function and not square root x.
Reply 168
Original post by Bright Lights
When proving trig, do you always need to start with the left hand side to prove the right hand side, or can you start from the RHS and work to the LHS? Asking because there are a few which I find easier/quicker to do the other way round.


Start from any side, but advice is to start from the side that is easier to equate to the other. Normally the longer side is easier to convert into the smaller side.
Reply 169
I'm going to start revision tomorrow.. only 10 days!! Seems like a long time but it will fly by!

How long do you think I should spend revising each day? (realistically)..
Reply 170
If anyone has a list of useful trig identities to learn (i.e all of them :tongue:) or if you know where I can find one please could you share :smile:

I keep finding more and more identities ITS STRESSING ME OUT :mad:

Much appreciated :smile:
Why is arcsin(sin(2pi/3)) equal to pi/3?
Reply 172
Original post by The_Pen
Just a quick question about functions. Why is f(x) = Square root x, a function if domain is x>=0, since it still remains a mapping of one-to-many (for every +/- y there is an x value).

Please reply.

f(x)=x,  x0f(x) = \sqrt x, \ \ x\geq 0

Is not a function, for the reasons you've given. However

f(x)=+x,  x0f(x) = + \sqrt x, \ \ x\geq 0

The modified version is usually used to comply with the function definition
Reply 173
Original post by Bright Lights
Why is arcsin(sin(2pi/3)) equal to pi/3?

I think you're confusing yourself. First

sin(2π3)sin(π3)\sin(\frac {2\pi}{3}) \equiv \sin(\frac {\pi}{3})

Then

arcsin(sin(x))x  or  sin1(sin(x))x\arcsin(\sin(x)) \equiv x \ \ or \ \ \sin^{-1}(\sin(x))\equiv x
hey guys, i was wondering whether anyone could help me solve this trig question:
Solve: 3cot2x + cotx = 1

Also, if possible, explain your method, haha :smile:
thanks!!
Original post by grazie
f(x)=x,  x0f(x) = \sqrt x, \ \ x\geq 0

Is not a function, for the reasons you've given. However

f(x)=+x,  x0f(x) = + \sqrt x, \ \ x\geq 0

The modified version is usually used to comply with the function definition


f(x)=xf(x) = \sqrt x is by definition equal to f(x)=+xf(x) = + \sqrt x. It would not be a function if it had the +- sign in front.
yhh +root x is a function with the parametres defined as x> or equal to 0, however ±root x isn't a function because y cannot be uniquely defined in terms of x, since many values of y map to one value of x
(edited 11 years ago)
Original post by Bubblezzzz
yhh +root x is a function with the parametres defined as x> or equal to 0, however ±root x isn't a function because y cannot be uniquely defined in terms of x, since many values of y map to one value of x


can i ask what the answers are to see if i am correct please
There was some trig identity that I just cannot remember! It was something to do with -sina or something I think. Apparently it never comes up but I still want to know it! Please help if anyone knows what on earth I'm on about
Original post by Bubblezzzz
hey guys, i was wondering whether anyone could help me solve this trig question:
Solve: 3cot2x + cotx = 1

Also, if possible, explain your method, haha :smile:
thanks!!


convert all cot to 1/tan
then basically use double angle identity for tan2x
you should get a quadratic
then solve the quadratic
in this domain -π/2<x<π/2 my ans. are π/4 and -1.03

quote me if the method is still not clear