How to Calculate Arctan
What is Arctan?
Arctan (inverse tangent, tan⁻¹) returns the angle whose tangent equals the input. Unlike arcsin and arccos, the domain is all real numbers (−∞, +∞).
Formula
θ = arctan(x) where tan(θ) = x
- x
- input value (tangent) — any real number (−∞, +∞)
- θ
- angle result (degrees or radians)
Step-by-Step Guide
- 1arctan(x) returns θ where tan(θ) = x
- 2Domain: all real numbers
- 3Range: (−90°, 90°) or (−π/2, π/2)
- 4arctan(1) = 45°, arctan(0) = 0°
Worked Examples
Input
arctan(1)
Result
45° or π/4 radians
Input
arctan(√3)
Result
60° or π/3 radians
Input
arctan(−1)
Result
−45°
Frequently Asked Questions
What is the domain and range of arctan?
Domain: all real numbers. Range: (−90°, 90°) or (−π/2, π/2) radians.
Why does arctan have a larger domain than arcsin and arccos?
Tangent is defined for all angles except ±90°, so its inverse also accepts all real values.
What is atan2 and how does it differ from arctan?
atan2(y, x) takes two arguments and returns the angle in the correct quadrant. arctan only uses one value.
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