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Trigonometric Functions Summary
PowerBASIC provides only four trigonometric functions, as listed in the following table. Note that all of these functions use angles specified as radians, not degrees.

Angle Argument (ratio out)	sin, cos, tan
Ratio Argument (angle out)	atn

Right Triangles
All of the trigonometric functions are related to right triangles - those with one 90 degree angle. The longest side (opposite the 90 degree angle) is called the hypotenuse. The other two sides have no standard nomenclature.

The trigonometric functions are simply the 3 possible ratios of all three sides. For any one of the two non-90 degree angles, the terminology of "side adjacent" refers to the non-hypotenuse side, as does the "side opposite".

The three possible ratios, when referring to a specific angle in the triangle, are named sine (opposite/hypotenuse), cosine (adjacent/hypotenuse) and tangent (opposite/adjacent).

Expanded Functions
Fortunately, these values can be used to generate other commonly used trignometric functions, as given in the following equations:

    csc = cosecant  =  1/sin  =  hypotenuse/opposite
    sec = secant    =  1/cos  =  hypotenuse/adjacent
    cot = cotangent =  1/tan  =  adjacent/opposite

Radians vs Degrees
The trignometric functions use radians - not degrees! Conversion factors are:

    1 degree = 0.0174533 radians
    1 radian = 57.29578 degrees
    pi radians = 180 degrees
    2*pi radians = 360 degrees

Also, here's a diagram showing the relationship of radians and degrees over a complete circle.

Trigonometric Functions Listing
Here are one-line descriptions of all the trigonometric functions.

• atn - arctangent (angle whose tangent is a specified number value)
• cos - cosine (side adjacent over hypotenuse)
• sin - sine (side opposite over hypotenuse)
• tan - tangent (side opposite over side adjacent)

• atn - arctangent

      result = atn(1)           ' result = .7894
      

• cos - cosine

      result = cos(0.7854)      ' result = 0.707
      

• sin - sine

      result = sin(0.7854)      ' result = 0.707
      

• tan - tangent

      result = tan(0.7854)      ' result = 1.0
      

If you have any suggestions or corrections, please let me know.