Arcsine Calculator

This arcsine calculator works out the inverse sine of a number, the angle whose sine equals the value you enter, which matters whenever you need to work backwards from a ratio to an angle rather than forwards from an angle to a ratio, something that comes up constantly in trigonometry, geometry, physics, surveying and navigation. You enter a single value, and it must sit between -1 and 1 inclusive, because sine itself can never produce a result outside that range, so anything beyond it has no real angle and the calculator will say so rather than force a false answer. Once you enter a valid figure, it returns the angle in degrees as the large headline result, the same angle again in radians alongside it, and your original input value repeated underneath so you can check what was calculated. It returns the principal value, the single standard answer arcsine gives, which always falls between -90 and 90 degrees (-pi/2 and pi/2 radians), even though other angles outside that band can share the same sine. Try the worked example of 0.5, which returns exactly 30 degrees because sin 30 equals 0.5, before entering your own figures. Results are rounded for display, so treat tiny decimal differences as rounding rather than a mistake.

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