ACS Function

ACS(real-expression)

Returns the arc cosine (inverse cosine) of the given expression, in radians. The input must be between -1 and 1.

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Examples

PRINT ACS(1)

Produces 0.

PRINT ACS(0)

Produces approximately 1.570796 (π/2).

PRINT ACS(-1)

Produces approximately 3.141593 (π).

REM Validate a cosine identity
angle# = 0.75
PRINT ACS(COS(angle#))

Produces the original angle (within floating point accuracy).

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Notes

• Argument range: -1 ≤ x ≤ 1. Values outside this range cause an error.
• Return range: 0 ≤ result ≤ π radians.
• To convert the result to degrees, multiply by 180 / PI.
• Inverse functions:
  • ASN (arc sine)
  • ATN (arc tangent)

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See also: COS · ASN · ATN · TAN