[Chapter 49] 49.4 bc's Sine and Cosine Are in Radians
Author: Jerry Peek, Tim O'Reilly & Mike Loukides
Date: 1998-08-04T21:56:40Z

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| Chapter 49 Working with Numbers |

## 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.

- MS in comp.unix.questions on Usenet, 19 April 1989

49.3 Gotchas in Base Conversion |  | 49.5 Base Conversion Using cvtbase