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-   -   "Waves" of sine expression (http://www.physicsforums.com/showthread.php?t=585450)

greggory Mar9-12 09:05 PM

"Waves" of sine expression
 
So, I have been working with a lot of Math today(sorry if I am asking so many questions), and I found and expression. All sine functions use radians.

sin(y) + sin(y) / sin(y)

Now, assuming you start with 1, if you were to plot y on a graph with variable x increasing each time calculated, you would get something like this:

http://betterexplained.com/wp-conten...itude_line.png

This image isn't mine, so this is just something identicle.

Can this be explained?

Vorde Mar9-12 10:00 PM

Re: "Waves" of sine expression
 
Two things.

First of all, the equation can be simplified. Depending on the use of parentheses, if you mean [itex]\ sin(y)[/itex]+[itex]\frac{ sin(y)}{ sin(y)}[/itex], this simplifies to [itex]\ sin(y)+1[/itex]

If you meant [itex]\frac{ sin(y)+ sin(y)}{ sin(y)}[/itex], this simplifies to the number 2.

In the latter case, it is a null statement, but assuming you meant the first equation, the sine function is defined in a couple of cool ways (the easiest being the ratio of the opposite and hypotenuse of a right triangle), and it turns out when you define a function that way it repeats itself like a wave.

greggory Mar9-12 10:51 PM

Re: "Waves" of sine expression
 
Thank you for the explanation. I was wondering why it did that(it was obvious, but any who).

But the expression sin(y) + sin(2*pi) / tan(y) does the same thing. Can that be explained?

HallsofIvy Mar10-12 06:44 AM

Re: "Waves" of sine expression
 
Because [itex]sin(2\pi)= 0[/itex]! And [itex]tan(y)= sin(y)/cos(y)[/itex] so that
[tex]\frac{sin(y)+ sin(2\pi)}{tan(y)}= \frac{sin(y)}{\frac{sin(y)}{cos(y)}}= sin(y)\frac{cos(y)}{sin(y)}= cos(y)[/tex]

Vorde Mar11-12 11:12 AM

Re: "Waves" of sine expression
 
And in a more general way, all of the trigonometric functions are periodic, so any combination of trig functions with also be periodic.


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