In MySQL, the COS() function returns the cosine of a given value, where the value is given in radians.

The cosine is the trigonometric function that is equal to the ratio of the side adjacent to an acute angle (in a right-angled triangle) to the hypotenuse.

Syntax

The syntax goes like this:

COS(X)

Where X is the value for which you’d like the cosine returned.

Example 1 – Basic Usage

Here’s a basic example to demonstrate what COS() returns for a given number.

SELECT COS(1);

Result:

+--------------------+
| COS(1)             |
+--------------------+
| 0.5403023058681398 |
+--------------------+

Example 2 – Using PI

In this example, I get the cosine of π (pi). I do this by passing in the PI() function as an argument.

SELECT COS(PI());

Result:

+-----------+
| COS(PI()) |
+-----------+
|        -1 |
+-----------+