# Why does my calculater calculate this wrong?

1. Mar 9, 2006

Or am I missing something here?

I need to find delta = arctan ( 1/48) and when I calculate that arctan (1/48) I find delta=1.19 but the answer is delta =0.0208 ( it seem opposite ?)

actually there was another question like that and I had the same problem there too. It seems everybody in the class know how it works accept me :((

2. Mar 9, 2006

### Hurkyl

Staff Emeritus
Always make sure your calculator is in the right mode when doing calculations.

I think your calculator is in degree mode. So, it gave you an answer in degrees. But, what you gave as the correct answer, seems to be in radians.

3. Mar 10, 2006

### HallsofIvy

Staff Emeritus
Your calculator is in "degree" mode and it should be in "radian" mode.

4. Mar 10, 2006

### BobG

I think Hurkyl and HallsofIvy addressed your problem, but it really shouldn't even get to that point. What is 1/48?

From around .1 radians or less, your angle (in radians) is approximately equal to the tangent of the angle and is also approximately equal to the sine of the angle (since the cosine is getting very close to 1, and tangent is sine over cosine). Technically, you would be reasonably close for a ways above .1 radians, but I generally go with what was used on the small angle tangent/sine scale on slide rules.