Math.asin()

The Math.asin() static method returns the inverse sine (in radians) of a number. That is,

{{InteractiveExample("JavaScript Demo: Math.asin()")}}

```js interactive-example // Calculates angle of a right-angle triangle in radians function calcAngle(opposite, hypotenuse) { return Math.asin(opposite / hypotenuse); }

console.log(calcAngle(6, 10)); // Expected output: 0.6435011087932844

console.log(calcAngle(5, 3)); // Expected output: NaN

## Syntax

```js-nolint
Math.asin(x)

Parameters#

• x
• : A number between -1 and 1, inclusive, representing the angle's sine value.

Return value#

The inverse sine (angle in radians between $-\frac{\pi}{2}$ and $\frac{\pi}{2}$, inclusive) of x. If x is less than -1 or greater than 1, returns {{jsxref("NaN")}}.

Description#

Because asin() is a static method of Math, you always use it as Math.asin(), rather than as a method of a Math object you created (Math is not a constructor).

Examples#

Using Math.asin()#

Math.asin(-2); // NaN
Math.asin(-1); // -1.5707963267948966 (-π/2)
Math.asin(-0); // -0
Math.asin(0); // 0
Math.asin(0.5); // 0.5235987755982989 (π/6)
Math.asin(1); // 1.5707963267948966 (π/2)
Math.asin(2); // NaN

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Math.acos()")}}
• {{jsxref("Math.atan()")}}
• {{jsxref("Math.atan2()")}}
• {{jsxref("Math.cos()")}}
• {{jsxref("Math.sin()")}}
• {{jsxref("Math.tan()")}}
• CSS {{cssxref("asin()")}} function