getSagitta function
Calculate circle segment sagitta.
Implementation
double getSagitta(double degrees, double radius) {
final chord = 2 * radius * math.sin(toRadians(degrees / 2));
/// Manipulate the sign to get the sagitta of the larger arc
final sign = degrees > 180 ? 1 : -1;
/// Arc sagitta is also the gauge widget height.
return radius +
sign * math.sqrt(math.pow(radius, 2) - math.pow(chord / 2, 2));
}