>But math never decreed that sine and cosine have to take radian arguments! To define trigonometric functions you need angles. Which can be measured in degrees

>But math never decreed that sine and cosine have to take radian arguments! To define trigonometric functions you need angles. Which can be measured in degrees or radians. If angles, degrees or radians wouldn't matter, those functions would be some ordinary real functions and not called "trigonometric". https://www.math.net/sine https://www.math.net/sine