The Calculator supports three notations for angles: radians, degrees,
and degrees-minutes-seconds. When a number is presented to a function
like `sin`

that requires an angle, the current angular mode is
used to interpret the number as either radians or degrees. If an HMS
form is presented to `sin`

, it is always interpreted as
degrees-minutes-seconds.

Functions that compute angles produce a number in radians, a number in
degrees, or an HMS form depending on the current angular mode. If the
result is a complex number and the current mode is HMS, the number is
instead expressed in degrees. (Complex-number calculations would
normally be done in Radians mode, though. Complex numbers are converted
to degrees by calculating the complex result in radians and then
multiplying by 180 over ‘`pi`’.)

The `m r` (`calc-radians-mode`

), `m d` (`calc-degrees-mode`

),
and `m h` (`calc-hms-mode`

) commands control the angular mode.
The current angular mode is displayed on the Emacs mode line.
The default angular mode is Degrees.