JavaScript Math sin() is a “static function used to calculate the sine of a number”. The Math.sin() function returns a numeric value between -1 and 1, representing the sine of the angle given in radians.
Syntax
Math.sin(x)
Parameter(s)
x: It is a number whose sine value is to be determined.
Return Value
The sine value is between -1 and 1.
Note
- The sin() method returns NaN if the passed value is empty.
Example 1: How to Use the sin() method
The following code demonstrates the use of the sin() method.
let a = 0;
let b = 1;
let c = Math.PI;
let d = 2 * Math.PI;
let e = (Math.PI) / 2;
console.log(Math.sin(a));
console.log(Math.sin(b));
console.log(Math.sin(c));
console.log(Math.sin(d));
console.log(Math.sin(e));
Output
0
0.8414709848078965
1.2246467991473532e-16
-2.4492935982947064e-16
1
Example 2: Passing an empty value to the Math sin() function
The following example demonstrates the case where an empty value is passed.
let x;
console.log(Math.sin(x));
console.log(Math.sin());
Output
NaN
NaN
Example 3: Passing a Pi as an argument
console.log(Math.sin(Math.PI / 2));
Output
1
Example 4: Real-world example
The following code example demonstrates applying the Math.sin() method in a simple programming context.
Given the base angle of the triangle and the base side, find all the remaining sides of the triangle.
// Given the base angle of a triangle and the base side,
// find all the remaining sides of the triangle.
let p;
let b;
let h;
let angle;
const r = require('readline');
const rl = r.createInterface({
input: process.stdin,
output: process.stdout
});
const prompt1 = () => {
return new Promise((resolve, reject) => {
rl.question('Base side: ', (answer) => {
b = answer;
resolve();
});
});
};
const prompt2 = () => {
return new Promise((resolve, reject) => {
rl.question('Base angle(in radians): ', (answer) => {
angle = answer;
resolve();
});
});
};
const main = async () => {
await prompt1();
await prompt2();
rl.close();
console.log('The three sides of the triangle are:');
console.log(b); //base side
let angle2 = (Math.PI) / 2 - angle;
h = b / (Math.sin(angle2));
console.log(h); //hypotenuse
p = h * Math.sin(angle);
console.log(p); //third side
}
main();
Output
Test Case 1:
Base side: 6
Base angle(in radians): 0.523599
The three sides of the triangle are:
6
6.928204127882605
3.464103410351597
Test Case2:
Base side: 30
Base angle(in radians): 0.785398
The three sides of the triangle are:
30
42.42639993882793
29.99999019615471
Browser Compatibility(Version and above)
- Google Chrome 1
- Internet Explorer 3
- Firefox 1
- Edge 12
- Opera 3
- Safari 1
- Android webview 1
- Chrome for Android 18
- Firefox for Android 4
- Opera for Android 10.1
- Safari on iOS 1
- Samsung Internet 1.0
- Node.js
JavaScript version: ECMAScript 1
That’s it.

Ankit Lathiya is a Master of Computer Application by education and Android and Laravel Developer by profession and one of the authors of this blog. He is also expert in JavaScript and Python development.