# Recent content by jing

1. ### Question about the use of Leibniz notations …

Double check what the text book actually wrote if it wrote (d/dx)*y to mean dy/dx then throw it away. More likely you have misinterpreted the text. Is it possible to scan the page and include it in your next post?
2. ### Humidifier physics homework

3. acos(h/r) is theta, ie half the angle of the sector at the centre. Need to double your result. 2 is submerged area + wet area above water 5 is submerged area for 6 you are working out wet area above water
3. ### Question about the use of Leibniz notations …

The article states that u*dy/dx + y*du/dx = d(y*u)/dx its the product rule
4. ### Question 21 - Final question on higher paper

thomas49th is taking what is called General Secondary Certficate Examination (GCSE) in Maths in England. It includes number, algebra, statistics and geometry and is taken at the age of 16. The examination is graded A,B,C,D,E,F, U (unclassified). Students achieving grades A or B will be allowed...
5. ### Question 21 - Final question on higher paper

Follow the instructions in my post #18 and do the drawing. You do know Pythagoras' Theorem don't you?
6. ### Question 21 - Final question on higher paper

NO ABSOLUTELY NOT. Just as Hallsof Ivy said. The webpage above is for vector displacement not distance between points. Lots of people have been pointing you in the right direction including me. Sometimes to follow advice you have to let go of the idea of what you were attempting was right...
7. ### Question 21 - Final question on higher paper

The question show in from an examination paper for GCSE. Thomas49th will have been given past examination papers for practice. The examination will take place in May. Thomas49th you will not have been shown the distance formula for GCSE but you will have covered pythagoras and should be able...
8. ### Another trigonometry problem

Depends on the wording of the question verify that x=180 is a solution of ..... use the first method show that x=180 is a solution of...... use the second method.
9. ### Another trigonometry problem

To verify x=180 is a solution LHS is sin(360)=0 RHS is 2 -2cos(360)=2-2=0 LHS=RHS so x=180 is a solution to obtain x=180 as a solution (1-cos2x)=(tanx)(sin2x) sin2x=2(1-cos2x) sin2x=2(tanx)(sin2x) sin2x-2tan(x)(sin2x)=0 sin2x(1-2tanx)=0 sin2x=0 or 1-2tanx=0
10. ### Expected Net Winning

The problem as stated by OP is the expected net winnings for the winner . I was querying whether this was what was actually asked.
11. ### Expected Net Winning

This gives that a player on average will lose $24.90 on a$100 dollar bet. Your questions asks for the expected net winnings for the winner so this is not the same thing. I was assuming this question was really about expected values and as you had had difficulty in finding anything about...
12. ### Trig Functions question

Not until you do some multiplying. Do you understand what I mean by the difference of two squares?
13. ### Expected Net Winning

This should help http://en.wikipedia.org/wiki/Expected_value
14. ### Trig Functions question

Do you know what the value of sec^2x-tan^2x is? The difference of two squares helps too.
15. ### Some Discreet Math stuff

try http://www.artofproblemsolving.com/Forum/viewtopic.php?t=130011&sid=30947c30f2e1b1fe60d2082b59b7fe3c