How to Calculate Arcsin
What is Arcsin?
Arcsin (inverse sine, sin⁻¹) returns the angle whose sine equals the input value. The output range is [−90°, 90°] or [−π/2, π/2] radians.
Formula
θ = arcsin(x) where sin(θ) = x
- x
- input value (sine) — must be in range [−1, 1]
- θ
- angle result (degrees or radians)
Step-by-Step Guide
- 1arcsin(x) returns θ where sin(θ) = x
- 2Domain: x ∈ [−1, 1]
- 3Range: [−90°, 90°]
- 4arcsin(0.5) = 30°, arcsin(1) = 90°
Worked Examples
Input
arcsin(0.5)
Result
30° or π/6 radians
Input
arcsin(1)
Result
90° or π/2 radians
Input
arcsin(−0.5)
Result
−30°
Frequently Asked Questions
What is the domain and range of arcsin?
Domain: [−1, 1]. Range: [−90°, 90°] or [−π/2, π/2] radians.
Why does arcsin only return angles up to 90°?
The principal range of arcsin is restricted to avoid ambiguity, since multiple angles can have the same sine value.
How is arcsin related to arccsc (arc cosecant)?
arcsin(x) = arccsc(1/x), just like sin and csc are reciprocals.
Ready to calculate? Try the free Arcsin Calculator
Try it yourself →