# Waves of sine expression

1. Mar 9, 2012

### greggory

"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:

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

Can this be explained?

2. Mar 9, 2012

### Vorde

Re: "Waves" of sine expression

Two things.

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

If you meant $\frac{ sin(y)+ sin(y)}{ sin(y)}$, 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.

3. Mar 9, 2012

### greggory

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?

Last edited: Mar 9, 2012
4. Mar 10, 2012

### HallsofIvy

Re: "Waves" of sine expression

Because $sin(2\pi)= 0$! And $tan(y)= sin(y)/cos(y)$ so that
$$\frac{sin(y)+ sin(2\pi)}{tan(y)}= \frac{sin(y)}{\frac{sin(y)}{cos(y)}}= sin(y)\frac{cos(y)}{sin(y)}= cos(y)$$

5. Mar 11, 2012

### Vorde

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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