docs: public static BigDecimal tan(BigDecimal x, MathContext mathContext) {
  		checkMathContext(mathContext);
  		if (x.signum() == 0) {
  			return ZERO;
  		}
  
  		MathContext mc = new MathContext(mathContext.getPrecision() + 4, mathContext.getRoundingMode());
  		BigDecimal result = sin(x, mc).divide(cos(x, mc), mc);
  		return round(result, mathContext);
  	}