# Quick calculator question

1. Jun 27, 2006

### sophzilla

Hello - I'm sorry if this question doesn't really apply here, but the Math & Science Tutorial wasn't very active so I decided to come here instead...

What should my calculator mode be in when graphing a hyperbolic WITH trigonometric function? (My function is sinx*coshx - sinhx*cosx). I'm getting 2 different graphs between radian and the degree mode.

I think it should be in the radian mode...?

2. Jun 27, 2006

What kind of calculator are you using?

I'll assume for a minute that you are using a TI-83/84. When you press the "WINDOW" key (next to "Y=") what is your X min, X max, Y min, Y max values?

The default is:
Xmin = -10
Xmax = 10
Ymin = -10
Ymax = 10

Lets say you are plotting $cos(x)$
Well from basic trig you know that:
$$cos(x=\frac{\pi}{2}) = 0$$
and that $\frac{\pi}{2}=90$
where $90$ is in degrees.

So if you have your default Xmin, Xmax, ... values above, then this means that you are allowing the calculator to start at the value of $-10$ and increment up to $10$.

If your calculator is in degree mode you will never see $cox(x)$ hit $0$. Do you see why this is? Our range is too small. But if you put your calculator in radian mode, then guess what... $\frac{\pi}{2}=1.571$ so we are within our range of values between -10 and 10, thus we will see something useful.

Also, if we let $y=cos(x)$. Then, $y$ will range from -1 to 1. So you only need to set
Ymin = -1
and
Ymax = 1

3. Jun 28, 2006

### FredGarvin

Pretty much any math class I have ever taken past high school used radians. I would suggest the same. It really doesn't matter which one you use as long as both functions get the same type of argument, either degrees or radians. Don't mix them.