Need some suggestions for good maths sites and /or books

Some one suggested mathcenter and someone suggested purplemath.com. I have now learnt all the math on this site and need some ideas for more advanced sites where I can continue to advance my knowledge. I am also open for books suggestions. I havent taken my a levels yet, but from self learning I am able to get a grades up to C4 with ease. I need books at a decent level. Also I want books that will properly explain the underlying priciples so that I can fully understand the maths. Thanks in advance.

Regards,
J. Lord

I have now learnt all the math on this site

With all due respect, what you have posted is not quit reality.
The posts you have made suggest a sketchy understanding and massive gaps in learning yet you leap from top end A2 work to even more challenging stuff.
An example would be not knowing basic trig identities such as cos2x. You will not be able to access C3/C4 effectively without this as a solid background.

My suggestion
Learn mathematics in a linear manner from the point of your real ability.
Start with C1, from the bottom, understanding what you are doing rather than just spotting formula and plugging numbers in.

Best books IMO?

Edexcel AS and A Level Modular Mathematics: Core Mathematics 1 and 2 by Keith Pledger, as it has solution bank too and quite user friendly

Longman alo do a very good book for both C1-C2 which is slightly harder than the current standards.

As above too, chandler and bostock is good although not for everybody.

At the end of the day, you ill muddle your way through maths with sketchy bits and bobs that don't link if you continue to pick random topics

I learnt trig identities yesterday. I had a free day and have now mastered them and the remaining topics. I

I learnt trig identities yesterday. I had a free day and have now mastered them and the remaining topics. I have managed to consistantly score 90 plus in C3 and i'm going to take some C4 papers today. Most A level math is very simple.

I bet you havent mastered them .

Here's a question if you have .It only requires two simple identities.
Find the sum : $cos^20+cos^22+cos^24....cos^2356+cos^2358+cos^2360$

All of your posts either shout
(i) I am very deluded
(ii) I want to create a reaction when I post

At the end of the day, the only people who award GCE A levels are the examining boards. When they issue you certfictes stating you have 90+ UMS across the 6 required units, I will say well done.
For now though I think the majority of what you type is either done to spark a response or to try and and prove somethig.
Stating you have mastered calculus in a previous thread outlines such issues yet didnt know basic trig identities.

As stated, buy a book, learn in a linear fashion and get your results.

3+cos4(1+2cos4)?

Nope.

Just get a book and do some problems untill you get really familiar with the identities (you might remember them , but working out when to use them is more important)

What's the answer then?

What's the answer then?