# [SOLVED] How do I find tan?

• Feb 10th 2009, 02:52 PM
RaphaelB30
[SOLVED] How do I find tan?
Instructions: Find value of Expression to nearest four significant digits.

tan 100°
• Feb 10th 2009, 02:56 PM
Jameson
Can you use a calculator? There are many approximation methods, the most common I think to use for this would be the Taylor series for tangent.
• Feb 10th 2009, 03:02 PM
RaphaelB30
Is there a simpler way or is calculator the easiest method?
• Feb 10th 2009, 03:06 PM
Jameson
I really don't know how your teacher wants you to do this. You could use the difference formula for tan(120-20) since 120deg = (2pi)/3 and 20deg=pi/9. Have you guys been doing angle sums in class?

edit: If you can't give some sort of direction then it won't be able to fully help you as like I said there are many ways to approximate trig functions. I can help you but I need info.
• Feb 10th 2009, 03:26 PM
RaphaelB30
ok, I found the tan of 120deg, but how do I find the tan of 20deg?

Edit: Yes. I believe I am learning angle sums.
• Feb 10th 2009, 03:52 PM
skeeter
Quote:

Originally Posted by RaphaelB30
Instructions: Find value of Expression to nearest four significant digits.

tan 100°

the instructions makes it clear what you need to do.

\$\displaystyle \tan(100) = -5.671\$
• Feb 10th 2009, 03:55 PM
Jameson
Haha thanks skeeter. To be honest I am blanking on a way to find tan20 by hand. I'm sure others know. Be patient.
• Feb 10th 2009, 03:58 PM
RaphaelB30
Quote:

Originally Posted by Jameson
You could use the difference formula for tan(120-20) since 120deg = (2pi)/3 and 20deg=pi/9. Have you guys been doing angle sums in class?

How would I do it this way? I already found sin of 120 deg.
• Feb 10th 2009, 04:00 PM
Jameson
If doing this by hand, you have to figure out a way to express tan20, which I can't think of right now.
• Feb 10th 2009, 04:00 PM
RaphaelB30
Never Mind
This problem wasn't intended to be that difficult. I think it was looking for the calculator way. Thanks very much Jameson and Skeeter.