The **`sinh()` function** returns the hyperbolic sine of a number in radians. 

The illustration below shows the mathematical representation of the `sinh()` function.

# 
## Syntax
```python
sinh(float $num): float
```
## Parameter
This function requires a number that represents an angle in radians as a parameter.

The following formula is used to convert degrees to radians.
```php
radians = degrees * ( M_PI / 180.0 )
```

## Return value
`sinh()` returns a number's hyperbolic sine (in radians), which is sent as a parameter.
 
* If the value of `num` is #key# NaN :not a number #key#, then the value returned is `NaN`. 

* If the value of `num` is positive infinity, then the value returned is positive infinity.  
* If the value of `num` is negative infinity, then the value returned is negative infinity. 
## Code


<?php
#Positive number in radians
echo ("sinh(2.3): ");
echo (sinh(2.3));
?>	
<?php
#Negative number in radians
echo ("sinh(-2.3): ");
echo (sinh(-2.3));
echo ("\n");
?>
<?php
#converting the degrees angle into radians and then applying sinh()
#degrees = 90
echo ("sinh(90 * (M_PI / (180))): ");
echo (sinh(90 * (M_PI / (180))));
?>

What is sinh() in PHP?

Returns a number's hyperbolic sine in radians. Handles NaN, positive and negative infinities appropriately.