# IB Math Helper

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1. ## Explain this trigonometry question please?

2cos(x) = sin(2x) 2cos(x) = 2sin(x)cos(x) cos(x) = sin(x)cos(x) cos(x)-sin(x)cos(x) = 0 cos(x) ( 1 - sin(x) ) = 0 So, cos(x) = 0 which means x = pi/2, 3*pi/2 and 5*pi/2 from 0 to 3*pi and sin(x) = 1 which means x = pi/2 and 5*pi/2 from 0 to 3*pi Hope this helps.
2. ## How to recognize which double angle formula to use?

If Sin(B)=2/3, you also need to know in which quadrant B is in. Otherwise, you can have two possible answers. For this question, the double angle is not necessary to find cos(B). Just draw a right angle triangle with the opposite side of 2 and hypotenuse of 3 and use Pythagoras to find the last side. Once you have that, the adjacent to the hypoteneuse is the ratio you want for cos(B).
3. ## Math IA Help

Go for it but explain it clearly (i.e. step-by-step) because the math here is beyond the scope of the curriculum.
4. ## Hat Check Problem - IA

This sounds like the secretary problem. Check out the math here: https://en.wikipedia.org/wiki/Secretary_problem
5. ## Page Limit for Math SL Internal Assessment (Exploration)

To clarify, there is no page limit. The recommended number of pages is between 6-12. However, that's just a recommendation. There are no points deducted for going over. Keep in mind though that more pages does not correlate with better quality. I suggest narrowing the focus on your essay so you can speak precisely about what is needed in your essay.
6. ## How does one go about writing a Math Exploration?

I don't agree that IB graders mark really hard. I'm an IB marker and I sometimes think the marking at times can be a little generous. It is true that it is hard to get a 7 on your IA but it's doable. If I were you, I would look at some more examples especially ones that scored very well. You can check this site out for some examples and read the comments the markers have given for each criteria. Check it out here: https://ibpublishing.ibo.org/live-exist/rest/app/tsm.xql?doc=d_5_matsl_tsm_1205_1_e&part=2&chapter=2
7. ## Math SL IA Topic Help

I would actually stick with the game theory idea since probability trees and expected values are still part of the math sl curriculum and of course tie in with game theory. The prisoner's dilemma, for example, can be modelled as a probability tree diagram and one can also find the expected value of the number of years in prison for different situations. If your game theory topics involves probability and statistics, you should stick with that.
8. ## Math Ia topic- similar to example

Plagiarism does NOT occur if you choose the same topic. Plagiarism does NOT occur if you use the same methods and mathematics. Plagiarism occurs if you take someone else's work and use it word for word. I highly doubt you have the exact wording in your IA. Which sample IA are you referring to by the way?
9. ## Continuing IB

The fear from the administration side is why you did it in the first place and what if you drop out again? Ask yourself that. Is the hassle, the pressing deadlines, tough content and confusing questions worth it? If so, then go for it. If not, then just focus on what you are doing right now.
10. ## Correlation between video length and watch time

It's definitely an exponential decay but you can also apply the damped sine graph if you want. Both work. You'll need to understand the formula of the damped sine graph and explain why it applies to your data. Generally speaking, the damped sine curve is used when the sine function slows down. For example, if you go bungee jumping the bungee cord exhibits a damped sine curve because it will eventually stop swinging. If you can figure this out, this will work well with your IA.
11. ## Correlation between video length and watch time

It's clear that the views per day drop exponentially. You can find the rate at which the two drop exponentially. So if y=Ae^(rx), then r is the rate of continuous growth (or decline in your case). Find this r value for both cases and compare why one is lower than the other.
12. ## how should i analyze this exponential graph for my math IA

Do you understand what this differential equation is? If not, it will be evident when you write your IA. My suggestion for you is this: Listen to everybody and then do what makes sense for you. If something doesn't make sense, don't do it.
13. ## Correlation between video length and watch time

If youtube allows you to view the number of videos per day, then you can construct a cumulative frequency curve vs time. This is a NOT a cumulative frequency graph. It's just a graph of the total views on the y-axis vs time on the x-axis. Hopefully you can use some of your older videos for this assuming they are not collecting as much views anymore. Once you've done this, you can then figure out equations to model those curves. You should look into logistic functions (they seem hard but they're really not) to model these kind of curves. They generally look like curves in the shape of an S with the top of and bottom of the S stretched sideways in opposite directions. I'm mentioning all of this because you might want to change your research question to the following: Why is it that two of your videos have a different number of views? That is, why did one video have explosive growth while the other may not have? You obviously want to pick two videos that have vastly different views. You can use your knowledge of the videos and the content in them to explain why one video might have appealed to a bigger audience than another. Hope this helps.
14. ## programs to get math equations into google docs

In a google word doc, go to Insert -> Equation. Use that to get your fractions and exponents typed up.
15. ## how should i analyze this exponential graph for my math IA

Try applying different models for the same data. For example, use a linear model and compare the differences (i.e. the residuals) between the data points and linear model. Check to see if a linear model is just as appropriate as an exponential model. If it is, great. If not, explain why not. Use the R^2 values as well for both models and discuss their differences as well. Also, you should explain what the R^2 value tells you since this is not taught in the IB Math SL curriculum.