# JavaScript Math sin()

The JavaScript Math.sin() function returns the sine of a specified number.

The syntax of the `Math.sin()` function is:

``Math.sin(x)``

`sin()`, being a static method, is called using the `Math` class name.

## Math.sin() Parameters

The `Math.sin()` function takes in:

• x - A number (in radians) whose sine value is required.

## Return value from Math.sin()

• Returns the sine of a given angle (a numeric value between -1 and 1).

## Example 1: Using Math.sin()

``````// sine of 1 radian
var value1 = Math.sin(1);
console.log(value1); // Output: 0.8414709848078965

// negative radians are allowed
var value2 = Math.sin(-2);
console.log(value2); // Output: -0.9092974268256817

// Math constants can be used
var value3 = Math.sin(Math.PI / 2);
console.log(value3); // Output: 1``````

Output

```0.8414709848078965
-0.9092974268256817
1```

## Example 2: Using Math.sin() with degrees

``````// custom function for angle in degrees
function sin(degrees) {
var radians = (degrees * Math.PI) / 180;
}

// sine of 57 degrees
value1 = sin(57);
console.log(value1); // Output: 0.8386705679454239

// sine of negative degrees
value2 = sin(-90);
console.log(value2); // Output: -1

value3 = sin(90);
console.log(value3); // Output: 1``````

Output

```0.8386705679454239
-1
1```

Here, we have defined a `sin()` function that converts the degree value to radian and then passes it to `Math.sin()`.

We can define custom functions in similar ways to extend the capabilities of such built-in functions.