Using these function will save you some time if you are doing A LOT of calculation.

class FastMath {

 static const double PI = Math.PI;
 static const double SQUARED_PI = PI * PI;
 static const double HALF_PI = 0.5 * PI;
 static const double TWO_PI = 2.0 * PI;
 static const double THREE_PI_HALVES = TWO_PI - HALF_PI;

 static const double _sin_a = -4 / SQUARED_PI;
 static const double _sin_b = 4 / PI;
 static const double _sin_p = 9 / 40;

 static const double _asin_a = -0.0481295276831013447;
 static const double _asin_b = -0.343835993947915197;
 static const double _asin_c = 0.962761848425913169;
 static const double _asin_d = 1.00138940860107040;

 static const double _atan_a = 0.280872;

 static double cos(final num x) => _TrigUtil.cos(x);
 static double sin(num x) => _TrigUtil.sin(x);
 static double tan(final num x) => sin(x) / cos(x);

 static double asin(num x) {
   x = x.toDouble();
   return x * (x.abs() * (x.abs() * _asin_a + _asin_b) + _asin_c) + signum(x) * (_asin_d - Math.sqrt(1 - x * x));
 }

 static double acos(num x) => HALF_PI - asin(x);

 static double atan(num x) {
   x = x.toDouble();
   return (x.abs() < 1) ? x / (1 + _atan_a * x * x) : signum(x) * HALF_PI - x / (x * x + _atan_a);
 }

 static int signum(num x) => (x < 0) ? -1 : (x > 0) ? 1 : 0;

}