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    Nov 2015
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  1. Since x is acute, it is found in the 3rd quadrant. All trigonometric values are thus positive. Draw a right-angled triangle with opposite = 1 and hypothenuse = 3 (since sin = opposite/hypothenuse) From this triangle, use Pythagorus to solve the last side. (which is equal to [sqrt(8)] ) cos x = adjacent/hypothenuse = [sqrt(8)] / 3 To find cos 2x use the double angle identity 1 - 2sin^2 (x) (you can use another identity but this one is easier since you already have to value of sin x This can be re-written as cos 2x = 1 - 2(sin(x))^2 = 1 - 2(1/3)^2 = 1 - 2 (1/9) = 1- (2/9) = 7/9 VoilÃ
  2. Welcome to the IB Diploma: pretty new to it myself, only been in the program for 7 months! Well I've always thought that a nice work-intensive start will yield better results than a slow one, especially if you have a chemistry teacher who perform poorly. Chemistry self-study can be quite hard, are you taking chemistry as HL or SL? I wouldn't mind figuring out how to stop procrastinating too! I try to keep my procrastination to this site however, so at least it can be productive! I use a TI-nspire CX and I love it. The TI-84 is also a good choice. Have fun!
  3. The TI-nspire CX CAS is only allowed for SATs and APs but you may use the TI-nspire CX for the IB examinations. Source: http://education.ti.com/sites/US/downloads/pdf/mini_testing_calendar.pdf
  4. We are also required by school to make use of the TI-nspire CX (which I find to be much easier to use than the other GDCs) but some of my classmates use the 84 plus and they get along fine so I don't think it makes much of a difference. When it comes to graphs I tend to prefer the colour display of the nspire cx though.
  5. We were suggested to do this too. The method has pros and cons though. The main advantage is that you don't waste much time in the initial stages of the paper but as you move back to the questions you've skipped you find yourself going through continuous topics you considered yourself not too confident about and that can be a heavy blow. As to my personal tips and tricks; I learned the formula booklet (almost) by heart so as not to waste time referring back to it. Mainly I try not to think too much about my areas of weakness.
  6. Seems like it depends on the school. Where I go our CAS coordinator insists on an adult supervisor to sign our activities.
  7. I have opted for the Chemistry HL course and quite frankly, it's not that difficult, but there is a lot of work that you need to be ready to invest into the subject to make it work. In my school we have mixed classes with the Chemistry SL students (not sure if its the same everywhere...) and most of them tend to find the subject manageable. It is a very time-consuming subject though. In terms of the difficulty of the final assessments my school typically produces very nice results in Chemistry but since I have yet to reach this stage myself I cannot say much about it. Good Luck!
  8. I think it all comes down to how interested you are in the topic; and a teacher capable of generating interest is essential in properly understanding and appreciating the options. That being said, here's my take on the difficulty in the options, from toughest to easiest. 1. Sets, relations and groups - we have not (and will not) done this option but from what I gather from the syllabus it seems to be the hardest. 2. Series and Differential Equations 3. Discrete Mathematics 4. Statistics and Probability
  9. Not very sure if its the same case everywhere but in my school self-taught activities do not contribute to CAS hours as there is no actual supervisor, as mentioned by Akmu above. The activities themselves should not be a problem though, you just need a supervisor for them. When it comes to action; if you are not much of an athletic person (like myself!) I would suggest diving as I found the sport to be very relaxing and it does not require much physical activity besides being able to swim.