N z r – HP 33s User Manual
Page 69
Real–Number
Functions
4–5
Example:
Show that cosine (5/7)
π radians and cosine 128.57° are equal (to four significant
digits).
Keys:
Display:
Description:
{}
Sets Radians mode; RAD
annunciator on.
5
7
)
5/7 in decimal format.
| N z R
. )
Cos (5/7)
π.
{}
. )
Switches to Degrees mode (no
annunciator).
128.57
R
. )
Calculates cos 128.57°, which
is the same as cos (5/7)
π.
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: # & . For a program,
then, it would be more reliable to determine
θ by a rectangular to polar conversion,
which converts (x,y) to (r,
θ). See "Coordinate Conversions" later in this chapter.