To find the sine of a number (in radians), we can use the php **sin()** function.

`sin(x)`

In php, we can easily use trigonometric functions from the collection of php math functions. These php math functions allow us to perform trigonometry easily.

To find the sine of a number, in radians, we use the php **sin()** function.

Below is the php syntax to find the sine of a number.

`sin(x)`

The input to the **sin()** function must be a float. The return value will be a float between -1 and 1.

```
echo sin(pi()/3); // 0.8660254037844386
echo sin(0); // 0.0
echo sin(pi()/2); // 1.0
```

## Converting Degrees to Radians for Input into sin()

The **sin()** function takes a number in radians as input. If your data is in degrees, you will need to convert the values to radians.

To convert degrees to radians, we can use the php deg2rad() function to convert the value to radians and then pass it to the **sin()** function.

```
echo sin(deg2rad(60)); // 0.8660254037844386
echo sin(deg2rad(0)); // 0.0
echo sin(deg2rad(90)); // 1.0
```

## Finding the Inverse Sine of a Number in php

With php, we can also find the inverses of the common trigonometric functions. The asin() function allows us to find the inverse of the sine of a number.

Below, we show that if we pass a number to **sin()** and then call the php **asin()** function, we get back the same number.

```
echo asin(sin(pi()/3)); // 1.0471975511965976
echo pi()/3; // 1.0471975511965976
```

## Finding the Cosecant of a Number in php

To find the cosecant of a number, we can divide 1 by the sine of the number.

We can find the cosecant of a number easily with the php **sin()** function. You can see how to find the cosecant of a number in the following php code.

`echo 1/sin(pi()/3); // 1.1547005383792517`

Hopefully this article has been beneficial for you to understand how to use the **sin()** function in php to find the sine of a number.

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