Inverse Sine Calculator
Find the angle whose sine equals a given value — returns arcsin in both degrees and radians.
How it works
- 1Enter a value between −1 and 1 — this is the sine of the unknown angle.
- 2The calculator applies arcsin (sin⁻¹) to find the unique angle in the principal range −90° to 90°.
- 3Results are shown in both degrees and radians so you can use whichever unit your problem requires.
Use cases
- Solving triangles: recover an angle from a known opposite ÷ hypotenuse ratio.
- Physics and engineering: convert a normalised component back to an angle.
- Maths coursework: verify hand-calculated arcsin results and build unit-circle intuition.
Frequently asked questions
Why is arcsin only defined for inputs in [−1, 1]?
Sine always produces values in [−1, 1], so only numbers in that range can be a sine of some angle. Inputs outside it have no real solution and the calculator returns —.
What is the principal range of arcsin?
arcsin returns angles in [−90°, 90°] (equivalently [−π/2, π/2] rad). This restricted range makes the function single-valued.
How do I convert the radian result to degrees?
Multiply radians by 180 ÷ π ≈ 57.2958. For example, arcsin(0.5) = π/6 rad × (180/π) = 30°.
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