JavaScript asin: How to Use Math.asin() in Javascript

 The asin() method comes in handy in programming contexts dealing with trigonometric expressions.

JavaScript Math.asin

Javascript Math asin() is a built-in function used to find the arcsine value in radians of a given argument. The Math.asin() function returns a numeric value between -pi/2 and pi/2 radians. Javascript asin() is a static method of Math. So, it is always used as Math.asin(), rather than as a method of the Math object.

To find the arcsine value of a given argument in JavaScript, you can use the Math.asin() method.

Syntax

Math.asin(x)

Parameters

The variable x lies between -1 and 1, whose arcsine value is to be determined.

Return Value

The arcsine value between -pi/2 and pi/2 radians.

See the following figure.

Note:

• If the passed value lies outside the range [-1,1], the method returns NaN.

Compatibility

• Google Chrome
• Internet Explorer
• Firefox
• Opera
• Safari
• Android webview
• Chrome for Android
• Firefox for Android
• Opera for Android
• Safari on iOS
• Samsung Internet
• Node.js

JavaScript version: ECMAScript 1

Consider the following examples

JavaScript Math asin() Code Example

See the following code.

// example1.js

var a = -1;
var b = 1;
var c = 0.5;
var d = 0;

console.log(Math.asin(a));
console.log(Math.asin(b));
console.log(Math.asin(c));
console.log(Math.asin(d));

Output

node example1
-1.5707963267948966
1.5707963267948966
0.5235987755982989
0

Example 2

The following example demonstrates the case where values outside the range of [-1,1] are passed as parameters.

// example2.js

var a = 2;
var b = -2;

console.log(Math.asin(a));
console.log(Math.asin(b));

Output

node example2
NaN
NaN

Example 3

The following code example demonstrates the application of this method in a simple programming context.

Given the three sides of a right-angled triangle, find all of its angles.

// example3.js

var h;
var b;
var p;

const r = require('readline');
const rl = r.createInterface({
  input: process.stdin,
  output: process.stdout
});

const prompt1 = () => {
  return new Promise((resolve, reject) => {
    rl.question('Hypotenuse: ', (answer) => {
      h = answer;
      resolve();
    });
  });
};

const prompt2 = () => {
  return new Promise((resolve, reject) => {
    rl.question('Base: ', (answer) => {
      b = answer;
      resolve();
    });
  });
};

const prompt3 = () => {
  return new Promise((resolve, reject) => {
    rl.question('Perpendicular: ', (answer) => {
      p = answer;
      resolve();
    });
  });
};

const main = async () => {
  await prompt1();
  await prompt2();
  await prompt3();
  rl.close();

  console.log('The three angles of the triangle are(in radians):');
  console.log(Math.asin(1)); 					//pi/2 radians
  console.log(Math.asin(p / h));				//base angle
  console.log(Math.asin(1) - Math.asin(p / h)); 		//third angle
}

main();

Output

Test Case 1:
->node example3
Hypotenuse: 6.928
Base: 6
Perpendicular: 3.464
The three angles of the triangle are:
1.5707963267948966
0.5235987755982989
1.0471975511965976

Test Case2:
->node example3
Hypotenuse: 42.426
Base: 30
Perpendicular: 30
The three angles of the triangle are(in radians):
1.5707963267948966
0.7854077535813886
0.785388573213508

See also

Javascript Math asinh()

JavaScript Math atan()

JavaScript Math atanh()

JavaScript Math atan2()

Javascript math cos()

Javascript math.cosh()

Javascript Math.abs()

Javascript Math.round()

Javascript Math.random()