How do you use sin, cos, and tan? (with the iPhone sdk)

I am not an iPhone developer, but as far as I know you should be able to include math.h which has all of these functions defined.

Noah is correct. Generally you can use any of the standard (BSD) C-runtime library functions with the iPhone SDK by #importing the required header. The quickest way to get the doc on any of these is from the Terminal command line. 'man math' will get you the list of all the math functions. 'man sin' will get the pages for sin(), sinl(), sinf(). The inverse circular and hyperbolic functions are named by prefixing an 'a'. So 'man asin' will bring up the pages for asin(), asinl(), asinf().