If the library function is not called, evaluate sin (X)

The first is the Taylor formula, but the formula brother does not remember it. If you are interested, it is not difficult to find out the implementation.

Second recursion, using three formulas

Sin (x) = 2 * sin (X/2) * Cos (X/2) -------------- Formula 1

Cos (x) = SQRT (1-sin (x) * sin (x) -------------- formula 2

Lim SiNx = x, when x tends to 0 ----------------- Formula 3

The problem of sin (X) is decomposed into the problem of sin (X/2), and then recursion is ended using Formula 3.

# Include <iostream> # include <math. h> using namespace STD; double ssin (Double X) {If (x <0.0000001) // defines an infinitely small return X; double result = ssin (X/2 ); return 2 * result * SQRT (1-result * result); // use Formula 1 and formula 2} int main () {Double X; CIN> X; fflush (stdin); cout <ssin (x) <Endl; getchar (); Return 0 ;}