public void Test_S1ChordAngle_Trigonometry()
{
const int kIters = 20;
for (int iter = 0; iter <= kIters; ++iter)
{
double radians = Math.PI * iter / kIters;
S1ChordAngle angle = new(S1Angle.FromRadians(radians));
Assert2.Near(Math.Sin(radians), angle.Sin(), S2.DoubleError);
Assert2.Near(Math.Cos(radians), angle.Cos(), S2.DoubleError);
// Since the tan(x) is unbounded near Pi/4, we map the result back to an
// angle before comparing. (The assertion is that the result is equal to
// the tangent of a nearby angle.)
Assert2.Near(Math.Atan(Math.Tan(radians)), Math.Atan(angle.Tan()), S2.DoubleError);
}
// Unlike S1Angle, S1ChordAngle can represent 90 and 180 degrees exactly.
S1ChordAngle angle90 = S1ChordAngle.FromLength2(2);
S1ChordAngle angle180 = S1ChordAngle.FromLength2(4);
Assert.Equal(1, angle90.Sin());
Assert.Equal(0, angle90.Cos());
Assert.Equal(double.PositiveInfinity, angle90.Tan());
Assert.Equal(0, angle180.Sin());
Assert.Equal(-1, angle180.Cos());
Assert.Equal(0, angle180.Tan());
}