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# `Cos`

 This reference topic applies to FQL v4. Go to this page for the latest FQL v10 reference topics.
``Cos( value )``
``cos( value )``
``Cos( value )``
``Cos( value )``
``Cos( value )``

## Description

The `Cos` function is a trigonometric function which calculates ratios of the lengths of the sides of right triangles. `Cos` returns the cosine of a number.

## Parameters

Parameter Type Definition and Requirements

`value`

Number

The Number whose cosine should be returned.

## Returns

A Number which is the cosine of `value`.

## Examples

The following query returns the cosine of 0.5:

``````client.query(
q.Cos(0.5)
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
'Error: [%s] %s: %s',
err.name,
err.message,
err.errors()[0].description,
))``````
``0.8775825618903728``
``````result = client.query(
q.cos(0.5)
)
print(result)``````
``0.8775825618903728``
``````result, err := client.Query(
f.Cos(0.5))

if err != nil {
fmt.Fprintln(os.Stderr, err)
} else {
fmt.Println(result)
}``````
``0.8775825618903728``
``````try
{
Value result = await client.Query(
Cos(0.5)
);

Console.WriteLine(result);
}
catch (Exception e)
{
Console.WriteLine(\$"ERROR: {e.Message}");
}``````
``DoubleV(0.8775825618903728)``
``Cos(0.5)``
``0.8775825618903728``
Query metrics:
•    bytesIn:  11

•   bytesOut:  31

• computeOps:   1

•   writeOps:   0