C in a Nutshell (In a Nutshell (OReilly))
Calculates the cosine of an angle #include <math.h> double cos ( double x ); double cosf ( float x ); (C99) double cosl ( long double x ); (C99)
The cos( ) function returns the cosine of its argument, which is an angle measure in radians. The return value is in the range -1 Example
/* * Calculate the sloping width of a roof * given the horizontal width * and the angle from the horizontal. */ #define PI 3.141593 #define DEG_PER_RAD (180.0/PI) double roof_pitch = 20.0; // In degrees double floor_width = 30.0; // In feet, say. double roof_width = 1.0 / cos( roof_pitch / DEG_PER_RAD ) * floor_width; printf( "The sloping width of the roof is %4.2f ft.\n", roof_width );
This code produces the following output: The sloping width of the roof is 31.93 ft.
See Also
sin( ), tan( ), acos( ), ccos( ) |