ArcCos Calculator
Find the angle whose cosine equals a given value, with principal value in degrees or radians.
Inputs
Must be between −1 and 1.
arccos(x)
60.00000000
Result (degrees)
60.000000°
Result (radians)
1.04719755
Step by step
Input value
= 0.5
Compute arccos
arccos(0.5)
= 60° = 1.04719755 rad
Principal range
= [0°, 180°]
How it works
The inverse cosine (arccos) returns the angle whose cosine equals x. The principal value is in [0°, 180°] or [0, π]. The domain is [−1, 1].
Formula
Inverse cosine
θ = arccos(x), where −1 ≤ x ≤ 1
- x
- The cosine value
- θ
- The resulting angle in [0°, 180°]
Frequently Asked Questions
What is arccos(0.5)?
arccos(0.5) = 60°, because cos(60°) = 0.5.
What is arccos(−1)?
arccos(−1) = 180°, the largest value in the principal range.