HP 33S Manual page 2

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HP 33S Solving Simple Trigonometry Problems
The trigonometric functions
The trigonometric functions, sine, cosine, tangent, and related functions, are used in geometry, surveying, and design.
They also occur in the solutions to orbital mechanics, integration, and other advanced applications.
The HP 33S provides the three basic functions, and their inverse, or "arc" functions. These work in degrees, radians and
gradians modes. In addition, π is provided as a function on the right-shifted "cos" key.
The secant, cosecant and cotangent functions are easily calculated using the n, k, and q keys respectively,
followed by ,. To help remember whether the secant function corresponds to the inverse sine or cosine, it can be
helpful to note that the first letters of "secant" and "cosecant" are inverted in relation to those of "sine" and "cosine", just
as the secant and cosecant are the inverted cosine and sine functions.
Trigonometric modes
The HP 33S can calculate trigonometric functions in any of these three modes: Degrees, Radians or Gradians.
Practice working problems involving trig functions
Example 1: Select the appropriate angle mode.
Solution: Press the Ý key below the screen.
Press 1, 2 or 3 to select DEGrees, RADians or GRADians mode, or use the arrow keys Ö,
Õ, × and Ø to select the required mode and then press Ï. For example, to select RAD,
press 2.
Answer: The selected trigonometric mode is displayed at the top of the screen if it is RAD or GRAD. If no angle
mode is shown, then the mode is degrees. The Ý command works the same way in algebraic and in
RPN modes.
There are 360 degrees, or 2 π radians in a circle. Gradians mode divides each quarter of a circle into 100
parts, in a sort of decimal system, making 400 gradians in a circle.
It is very easy to forget that one angle mode is set but angles are being entered in a different mode. Making
it a habit to check the angle mode is a good policy. The commands DEG, RAD and GRAD can be entered
into programs, and it is worth using them to be sure that a program will work as required.
hp calculators - 2 - HP 33S Solving Simple Trigonometry Problems - Version 1.0
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