JavaScript And DHTML Cookbook [Electronic resources] نسخه متنی

2.8 Calculating Trigonometric Functions

NN 2, IE 3

2.8.1 Problem

You want to invoke a
variety of trigonometric functions, perhaps for calculating animation
paths of a positioned element.

2.8.2 Solution

JavaScript's
Math object comes with a typical
complement of functions for trigonometric calculations. Each one
requires one or two arguments and returns a result in radians.
Arguments representing angles must also be expressed in radians. The
following statement assigns the sine of a value to a variable:

var sineValue = Math.sin(radiansInput);

All Math object methods must be invoked as methods
of the static Math object.

2.8.3 Discussion

See the introduction to this chapter for a summary of all
Math object methods and constants. You can see an
application of trigonometric functions in Recipe 13.10, which
calculates the circular path for a positioned element to follow on
the page.

2.8.4 See Also

Section 2.0.2 in the
introduction of this chapter; Recipe 13.10 where some trigonometric
operations help calculate points around a circular path.