# Recent content by okeydonkey

1. ### [Simple Harmonic Question] I don't how to approach the question

Hi, thank you so much for your help. How do you know when to use x = acos(nt+b) and x=sin(nt+b) since I was taught both ways. Also,why is that "the particle starts from rest, so this point would be a turning point on its cos graph"? Why must it be the turning point? Thank you!
2. ### My answer doesn't match the solution. What did I do wrong? (Binomial Probability)

I got it. Thank you!
3. ### [Simple Harmonic Question] I don't how to approach the question

Hi could someone please help me with the following question? Thank you so much for the help! A particle moving in Simple Harmonic Motion starts from rest at a distance 10 metres to the right of its centre of oscillation O. The period of the motion is 2 seconds. i. Find the speed of the particle...
4. ### My answer doesn't match the solution. What did I do wrong? (Binomial Probability)

The following question has multiple parts and I am getting stuck on the final part. I don't think the last part has anything to do with the previous parts but I am going to include those as well just in case. Two sport fans applied for Olympic finals tickets in athletics, basketball, hockey...
5. ### I don't know how I got the answer for this binomial probability question! (The answer is correct but I don't understand my working out)

Thank you so much for the help!
6. ### I don't know how I got the answer for this binomial probability question! (The answer is correct but I don't understand my working out)

For this question, my original working out gave me a result that was greater than 1 which was obviously wrong for probability so I sort of guesstimated the working out and finally got the answer but I don't understand the logic behind this working out (assuming that my working out is right. If...
7. ### Binomial Probability Question - What is wrong with my working out?

ouch! you're right! thank you!
8. ### Binomial Probability Question - What is wrong with my working out?

Hi everyone, I am getting stuck on the following question since I cannot get an answer like the solution. The probability of a particular team winning a match is 0.6, the probability of the team losing is 0.3 and the probability of a draw is 0.1. Two points are awarded for a win, one for a...
9. ### Where to find resources for new 4u topics like 3D vectors?

Hi everyone, I have an exam which has 3D vector as one of the topics so I wonder where to find more resources on this topic. All suggestions are highly appreciated!
10. ### [Inverse Trig] Why does the solution only take into consideration 1 case?

Thank you everyone!
11. ### [Inverse Trig] Why does the solution only take into consideration 1 case?

I guess so. How about tan inverse? Is it also from pi/2 to -pi/2 like sine inver
12. ### [Inverse Trig] Why does the solution only take into consideration 1 case?

Hi I am a bit confused by the solution of the following question. In the solution, it automatically assumes that tan(alpha) is negative but if sin(alpha) is negative then alpha can either be in the third quadrant or the fourth quadrant which means that tan(alpha) can either be positive or...
13. ### doing 4 tutoring classes (2 places) for maths (2 for 3u and 2 for 4u). Should I quit 1 place?

Hi there, the title pretty much speaks for itself. I just joined Dr Du 3u and 4u maths last term and I can always barely catch up with the homework they give (2 very hard 20-page hw booklets; 1 for each 3u and 4u). It is just too much and on top of that, I have maths hw from another maths tutor...
14. ### anyone go to Dr Du right now?

Hi is there anyone in the forum who's currently doing 4u maths at Dr Du at Burwood? Does he actually teach or the teacher is an ex-student? Is the teaching good? What topic are you guys up to and if I join now, can I ask for resources of earlier topics? And also, what topics does the entrance...
15. ### Is it too late to start revising for the new term now? And what are the most effective ways to do it?

Hi all, I am currently on holiday and since I have been so busy enjoying the past three weeks to the fullest, I just did an average of one hour of study per day. Now I sort of regret that I did not study more. Is it too late to get serious now? How many hours of daily study should I do if I want...