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# addRelativeArc(center:radius:startAngle:delta:transform:)

Adds an arc of a circle to the path, specified with a radius
and a difference in angle.

```
mutating func addRelativeArc(center: CGPoint, radius: CGFloat, startAngle: Angle, delta: Angle, transform: CGAffineTransform = .identity)
```

## Parameters

`center`

The center of the arc, in user space coordinates.

`radius`

The radius of the arc, in user space coordinates.

`startAngle`

The angle to the starting point of the arc,
measured from the positive x-axis.

`delta`

The difference between the starting angle and ending
angle of the arc. A positive value creates a counter-
clockwise arc (in user space coordinates), and vice versa.

`transform`

An affine transform to apply to the arc before
adding to the path. Defaults to the identity transform if
not specified.
/

## Discussion

This method calculates starting and ending points using the
radius and angles you specify, uses a sequence of cubic
Bézier curves to approximate a segment of a circle
between those points, and then appends those curves to the
path.

The `delta` parameter determines both the length of the arc the
direction in which the arc is created; the actual direction of
the final path is dependent on the `transform` parameter and
the current transform of a context where the path is drawn.
However, because SwiftUI by default uses a vertically-flipped
coordinate system (with the origin in the top-left of the
view), specifying a clockwise arc results in a counterclockwise
arc after the transformation is applied.

If the path ends with an unclosed subpath, this method adds a
line connecting the current point to the starting point of the
arc. If there is no unclosed subpath, this method creates a new
subpath whose starting point is the starting point of the arc.
The ending point of the arc becomes the new current point of
the path.

---

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