TI-89 Titanium graphing problem

[irelandmc]

Hi all, found this forum while looking for a solution to this problem:

When I graph a y1=sin(x) I get the sin wave you would expect.

but...

When I graph y2=5+4*sin(pi/12)(x+10) I get a line instead of a wave?

What gives? I'm in radian, I reset my factory defaults... Am I entering this wrong? Shouldn't that give you a sin wave?

Thanks for your help!

 

[irelandmc]

http://fooplot.com/5+4sin(pi/12)(x+10)"

You have to pan left to about x=-15 to see it

Well, fooplot gave me the same thing, so why am I expecting this to be a sin wave?

 

[ravenprp]

Hi there,

It seems like you may have made a mistake with your parentheses when entering the equation for y2. The correct way to enter it would be y2=5+4*sin((pi/12)*(x+10)). Notice the extra set of parentheses around pi/12 and (x+10). This will ensure that the entire expression is being multiplied by 4, rather than just the x value.

Also, make sure that you are in radian mode when graphing. If you are still having trouble, try resetting your calculator to factory defaults again and double check your parentheses. I hope this helps!