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ACOS()

Overview

ACOS() returns the arc cosine (inverse cosine) of a number in radians. The arc cosine is the angle whose cosine is the specified number. The input value must be between -1 and 1, inclusive. If the input is invalid (outside this range), the function returns zero.

Function Format 

ACOS(number)

Return Value 

ACOS() returns a numeric value in radians between 0 and π (approximately 3.14159)

Examples 


ACOS(0)         = 1.5708  (π/2 radians)
ACOS(COS(0))    = 0
ACOS(COS(1))    = 1
ACOS(COS(PI())) = 3.1416  (π radians)
ACOS(1)         = 0
ACOS(-1)        = 3.1416  (π radians)

Notes

  • The input value must be between -1 and 1, inclusive.
  • If the input is outside this range, the function returns 0.
  • The result is always in radians, not degrees.
  • To convert the result to degrees, multiply by (180/π).
  • This function is commonly used in trigonometric calculations and geometry.

See Also