HP 35s Scientific Calculator User Manual
Page 79
4-5
Example:
Show that cosine (5/7)
π radians and cosine 128.57° are equal (to four significant
digits).
Programming Note:
Equations using inverse trigonometric functions to determine an angle
θ, often look
something like this:
θ
= arctan (y
/x).
If x = 0, then y
/
x is undefined, resulting in the error: .
Keys:
Display:
Description:
9
()
Sets Radians mode; RAD
annunciator on.
5/7 in decimal format.
Cos (5/7)
π.
9
()
Switches to Degrees mode (no
annunciator).
Calculates cos 128.57°, which is
the same as cos (5/7)
π.