When to use this calculator
Use inverse sine when you know opposite-side length divided by hypotenuse and need the principal angle.
Explore the trigonometry calculators for other questions in this topic. For a related calculation, use the Arctangent Calculator: Find the principal angle corresponding to a tangent ratio.
PUTTING IT INTO PRACTICE
Arcsine: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Sine ratio | 0.5 |
| Result | 30 degrees |
- Check the input labels and enter the example values above.
- Apply the relationship: Angle = asin(ratio) × 180/π.
- The result is 30 degrees, rounded for display.
How to interpret your result
Returns the principal angle from −90° to 90°. Other angles can have the same sine.
These tools take degrees unless stated otherwise. A right-triangle ratio and the law of cosines solve different input patterns. For the sine rule, identify which side is opposite each supplied angle.
Frequently asked questions
Are the angle inputs in degrees or radians?
The trigonometry tools here label angles in degrees and convert internally. Use the degree-to-radian converter when another formula requires radians.
When is the arcsine calculator useful?
Use inverse sine when you know opposite-side length divided by hypotenuse and need the principal angle.
How do I use the arcsine calculator?
Enter sine ratio. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Angle = asin(ratio) × 180/π.
What should I check before using the result?
Returns the principal angle from −90° to 90°. Other angles can have the same sine.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see OpenStax: basic functions and identities ↗. This is a topic reference, not an external review or endorsement of this tool.
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