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# UnitAngle

A unit of measure for planar angle and rotation.

```
class UnitAngle
```

## Overview

You typically use instances of [`UnitAngle`](/documentation/Foundation/UnitAngle) to represent specific quantities of planar angle using the [`NSMeasurement`](/documentation/Foundation/NSMeasurement) class.

### Angle

Angle is a quantity of rotation. The SI unit for angle is the radian (rad), which is dimensionless and defined to be the angle subtended by an arc that is equal in length to the radius of a circle. Angle is also commonly expressed in terms of degrees (°) and revolutions (rev).

The [`UnitAngle`](/documentation/Foundation/UnitAngle) class defines its [`baseUnit()`](/documentation/Foundation/Dimension/baseUnit()) as [`degrees`](/documentation/Foundation/UnitAngle/degrees), and provides the following units, which are initialized using [`UnitConverterLinear`](/documentation/Foundation/UnitConverterLinear) converters with the specified coefficients:

|Name       |Method                                                                       |Symbol|Definition  |
|-----------|-----------------------------------------------------------------------------|------|------------|
|Degrees    |``doc://com.apple.foundation/documentation/Foundation/UnitAngle/degrees``    |°     |`1.0`       |
|Arc Minutes|``doc://com.apple.foundation/documentation/Foundation/UnitAngle/arcMinutes`` |ʹ     |`0.016667`  |
|Arc Seconds|``doc://com.apple.foundation/documentation/Foundation/UnitAngle/arcSeconds`` |ʺ     |`0.00027778`|
|Radians    |``doc://com.apple.foundation/documentation/Foundation/UnitAngle/radians``    |rad   |`57.2958`   |
|Gradians   |``doc://com.apple.foundation/documentation/Foundation/UnitAngle/gradians``   |grad  |`0.9`       |
|Revolutions|``doc://com.apple.foundation/documentation/Foundation/UnitAngle/revolutions``|rev   |`360`       |

## Topics

### Accessing the Base Unit

[`baseUnit()`](/documentation/Foundation/Dimension/baseUnit())

Returns the base unit.

### Accessing Predefined Units

[`degrees`](/documentation/Foundation/UnitAngle/degrees)

The degrees unit of angle.

[`arcMinutes`](/documentation/Foundation/UnitAngle/arcMinutes)

The arc minutes unit of angle.

[`arcSeconds`](/documentation/Foundation/UnitAngle/arcSeconds)

The arc seconds unit of angle.

[`radians`](/documentation/Foundation/UnitAngle/radians)

The radians unit of angle.

[`gradians`](/documentation/Foundation/UnitAngle/gradians)

The gradians unit of angle.

[`revolutions`](/documentation/Foundation/UnitAngle/revolutions)

The revolutions unit of angle.


---

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