49.4 bc's Sine and Cosine Are in Radians

While using the bc utility the other day, I had the occasion to use the arbitrary precision math library, which is the option -l (lowercase letter "l") of this utility. I wanted to do a simple computation involving the sine of an angle.

I assumed, after reading the manual page, that all I had to do was put in the angle (in degrees) in the sine function. For example, the sine of 30 degrees would be given by:

s(30)

However, this didn't work. A little investigation revealed that the angle shouldn't be in degrees but in radians. For example, the sine of 30 degrees or 0.5263 radians,

s(.5263)

gives the correct answer of 0.5.

This is also true of the cosine function.