Owner's handbook and programming guide, HP-41C

Section 6: Functions

To see the RAD and GRAD annunciators in the display...

Keystrokes

Display

XEQ

–

XEQ _ _

ALPHA RAD ALPHA

0.0000

Notice that the RAD annunciator turns on. (The number in the display remains from the previous example.)

– 8.5 106
	RAD

XEQ

–

XEQ _ _

ALPHA GRAD ALPHA

0.0000

Notice that the GRAD annunciator turns on.

– 8.5 106
	GRAD

Note: 360 degrees = 2π radians = 400 grads

Trigonometric Functions

There are 6 trigonometric functions provided by the HP-41C. Both the keyboard form and the display execution form of the function are given: keyboard form first.

	SIN (sine)

	SIN–1 or ASIN (arc sine)

	COS (cosine)

	COS–1 or ACOS (arc cosine)

	TAN (tangent)

	TAN–1 or ATAN (arc tangent)

Each of these trigonometric functions assume that angles are entered in decimal degrees, radians, of grads, depending upon the trigonometric mode selected.

All trigonometric functions are one-number functions, so to use them, you key in the number, then execute the function. For example, find the cosine of 35 degrees.