# How the COS() function works in Mariadb?

The `COS()`

function is a mathematical function that returns the cosine of a given angle. The function returns a decimal value between -1 and 1, representing the cosine of the angle in radians.

The `COS()`

function is a mathematical function that returns the cosine of a given angle. The function returns a decimal value between -1 and 1, representing the cosine of the angle in radians. The function can handle angles in degrees, by using the `RADIANS()`

function to convert them to radians.

## Syntax

The syntax of the `COS()`

function is as follows:

```
COS(angle)
```

The function takes one argument, `angle`

, which is the angle to be calculated. The argument can be a number or an expression that evaluates to a number. The function returns NULL if the argument is NULL or invalid.

## Examples

### Example 1: Calculating the cosine of a zero angle

The following example uses the `COS()`

function to calculate the cosine of a zero angle.

```
SELECT COS(0);
```

The output is:

```
+--------+
| COS(0) |
+--------+
| 1 |
+--------+
```

The output shows that the cosine of a zero angle is 1, as expected.

### Example 2: Calculating the cosine of a 90-degree angle

The following example uses the `COS()`

function to calculate the cosine of a 90-degree angle. The angle is converted to radians by using the `RADIANS()`

function.

```
SELECT COS(RADIANS(90));
```

The output is:

```
+-----------------+
| COS(RADIANS(90)) |
+-----------------+
| 0 |
+-----------------+
```

The output shows that the cosine of a 90-degree angle is 0, as expected.

### Example 3: Calculating the cosine of a negative angle

The following example uses the `COS()`

function to calculate the cosine of a negative angle. The angle is -45 degrees, which is equivalent to 315 degrees.

```
SELECT COS(RADIANS(-45));
```

The output is:

```
+------------------+
| COS(RADIANS(-45)) |
+------------------+
| 0.70710678118655 |
+------------------+
```

The output shows that the cosine of a negative angle is the same as the cosine of the corresponding positive angle, as expected.

### Example 4: Calculating the cosine of a large angle

The following example uses the `COS()`

function to calculate the cosine of a large angle. The angle is 720 degrees, which is equivalent to 0 degrees.

```
SELECT COS(RADIANS(720));
```

The output is:

```
+------------------+
| COS(RADIANS(720)) |
+------------------+
| 1 |
+------------------+
```

The output shows that the cosine of a large angle is the same as the cosine of the angle modulo 360 degrees, as expected.

### Example 5: Calculating the cosine of an invalid angle

The following example uses the `COS()`

function to calculate the cosine of an invalid angle. The angle is a string that cannot be converted to a number.

```
SELECT COS('Hello');
```

The output is:

```
+-----------+
| COS('Hello') |
+-----------+
| NULL |
+-----------+
```

The output shows that the function returns NULL, as expected. The function returns NULL if the argument is NULL or invalid.

## Related Functions

There are some other functions that are related to the `COS()`

function in Mariadb. They are:

`SIN()`

: This function returns the sine of a given angle.`TAN()`

: This function returns the tangent of a given angle.`ACOS()`

: This function returns the arc cosine of a given value.`RADIANS()`

: This function converts an angle in degrees to radians.`DEGREES()`

: This function converts an angle in radians to degrees.

## Conclusion

The `COS()`

function is a useful function to calculate the cosine of a given angle. It returns a decimal value between -1 and 1, representing the cosine of the angle in radians. It can handle angles in degrees, by using the `RADIANS()`

function to convert them to radians. It is similar to the `SIN()`

and `TAN()`

functions, but with a different trigonometric ratio. It is also related to some other functions that provide inverse or conversion operations on angles or values.