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Atn Function

## Syntax

`Atn(`number`)`
`number`

Use: Required

Data Type: Numeric

Any numeric expression, representing the ratio of two sides of a right angle triangle.

## Return Value

The return value is a Double representing the arctangent of `number` in the range -pi/2 to pi/2 radians.

## Description

Takes the ratio of two sides of a right triangle (`number`) and returns the corresponding angle in radians. The ratio is the length of the side opposite the angle divided by the length of the side adjacent to the angle.

## Rules at a Glance

• If no number is specified, a runtime error is generated.

• The return value of Atn is in radians, not degrees.

## Example

```<%
Const Pi = 3.14159
Dim dblRatio, dblAtangent, dblDegrees

dblSideOpp = 75.5

dblAtangent = Atn(dblRatio)
' convert from radians to degrees
dblDegrees = dblAtangent * (180 / Pi)
Response.Write dblDegrees & " Degrees"
%>```

## Programming Tips and Gotchas

• To convert degrees to radians, multiply degrees by pi/180.