# Idle curiousity

• Dec 4th 2012, 07:38 AM
Nervous
Idle curiousity
How do I evaluate a trig function like $sin(4)$ without a calculator? Assuming that, since there is no unit, it's 4 radians...
• Dec 4th 2012, 07:46 AM
Plato
Re: Idle curiousity
Quote:

Originally Posted by Nervous
How do I evaluate a trig function like $sin(4)$ without a calculator? Assuming that, since there is no unit, it's 4 radians...

I would look it up in a trig table.
• Dec 6th 2012, 02:02 PM
Nervous
Re: Idle curiousity
How would I construct a trig table?
• Dec 6th 2012, 02:25 PM
skeeter
Re: Idle curiousity
Quote:

Originally Posted by Nervous
How would I construct a trig table?

http://www.math.rutgers.edu/~cherlin...2000/hunt.html
• Dec 6th 2012, 04:51 PM
HallsofIvy
Re: Idle curiousity
Although it is NOT the way trig tables are constructed, the simplest thing to do is to use "MacLaurin" series for sin(x):
$sin(x)= x- \frac{x^3}{3!}+ \frac{x^5}{5!}- \frac{x^7}{7!}+ \cdot\cdot\cdot+ \frac{x^{2n+1}}{(2n+1)!}+ \cdot\cdot\cdot$