1弧度= 180°/π 1度=（1弧度 * π）/180
https://www.rapidtables.com/convert/number/radians-to-degrees.html

你可以使用一个正则表达式函数在操作之前转换用户输入：

String replaceTrigFunctionsWithTransformation(String input) {
    final RegExp trigFunctionRegex = RegExp(r'(sin|cos|tan)\(([^)]+)\)');

    String result = input;
    for (Match match in trigFunctionRegex.allMatches(input)) {
      final originalMatch = match.group(0); // e.g., sin(45)
      final trigFunction = match.group(1); // e.g., sin
      final innerExpression = match.group(2); // e.g., 45

      if (originalMatch != null &&
          trigFunction != null &&
          innerExpression != null) {
        // Replace sin(45) with sin((pi/180)*(45))
        final transformedExpression =
            '$trigFunction((π/180)*(${innerExpression.trim()}))';
        result = result.replaceFirst(originalMatch, transformedExpression);
      }
    }

    return result;
  }

个字符