ACOS Function (LibreOffice Calc)

• Computes the inverse cosine of a value
• Returns an angle in radians
• Accepts values in the range –1 to 1
• Useful for triangle calculations, vector math, and geometric modeling

ACOS(number)

Arguments

• number:
  A numeric value between –1 and 1 inclusive.

Arccosine of a value

=ACOS(0.5)
→ 1.047197551 (radians)

Convert result to degrees

=DEGREES(ACOS(0.5))
→ 60

Using a cell reference

=ACOS(A1)

Compute angle between two vectors

=ACOS( (A1*B1 + A2*B2) / (SQRT(A1^2 + A2^2) * SQRT(B1^2 + B2^2)) )

Compute angle in a triangle using the Law of Cosines

=DEGREES(ACOS((b^2 + c^2 - a^2) / (2*b*c)))

Normalize input to avoid domain errors

=ACOS(MAX(-1; MIN(1; A1)))

Combine with RADIANS for geometric modeling

=COS(RADIANS(ACOS(A1)))

ACOS returns a numeric value (radians)

Accepts:

• Numbers between –1 and 1
• Expressions that evaluate to numbers

Invalid input → Err:502

Behavior details

• Input must be in the closed interval [–1, 1]
• Output is in radians, not degrees
• ACOS is undefined for values outside the domain
• Use DEGREES() to convert the result

ACOS of an error → error propagates

• Always convert to degrees when working with human‑readable angles
• Clamp floating‑point results to avoid domain errors
• Use ACOS with vector dot products for geometric modeling
• Combine with PI(), SIN(), COS(), and ATAN for full trigonometric workflows

• Use COS for forward cosine
• Use ASIN and ATAN for other inverse trig functions
• Use DEGREES and RADIANS for angle conversion
• Use PI() for circle and rotation calculations

By mastering ACOS and its companion functions, you can build precise, reliable trigonometric and geometric models in LibreOffice Calc.