Arccos Calculator - Inverse Cosine (Degrees and Radians)

Your details

Any number from -1 to 1. Values outside this range are undefined for the real arccos function.
Controls which unit is highlighted as the primary result. Both values are always shown.
Angle (degrees)Acute angle
60deg

arccos(x) expressed in degrees, range 0 to 180

Angle (radians)1.047198rad
Radian fractionpi/3
Verification: cos(result)0.5
1.047198 rad25.2% below · arccos(x) output (radians)

arccos(0.5) = 60.0000 degrees (1.047198 rad)

  • This is an exact value: arccos(0.5) = pi/3 radians = 60.00000000000001 degrees.
  • 60.0000 degrees is an acute angle (less than 90 degrees), which means x is positive.
  • The supplementary angle is 120.0000 degrees. Note that cos(60.0000 deg) = 0.500000 and cos(120.0000 deg) = -0.500000.

Next stepTo convert to the full-circle inverse cosine (range 0 to 360 degrees) you need additional context about which quadrant the original angle was in, since arccos only covers 0 to 180 degrees.

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