HP 35s User Manual page 79

Example:
Show that cosine (5/7) radians and cosine 128.57° are equal (to four significant
digits).
Keys:
9
()

   
9
()


Programming Note:
Equations using inverse trigonometric functions to determine an angle , often look
something like this:
If x = 0, then y x is undefined, resulting in the error:   .
Display:




= arctan (y x).
Description:
Sets Radians mode; RAD
annunciator on.
5/7 in decimal format.
Cos (5/7) .
Switches to Degrees mode (no
annunciator).
Calculates cos 128.57°, which is
the same as cos (5/7) .
Real–Number Functions
4-5