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# CGPathAddRelativeArc

Appends an arc to a mutable graphics path, possibly preceded by a straight line segment.

```
extern void CGPathAddRelativeArc(CGMutablePathRef path, const CGAffineTransform *matrix, CGFloat x, CGFloat y, CGFloat radius, CGFloat startAngle, CGFloat delta);
```

## Parameters

`path`

The mutable graphics path to change.

`matrix`

A pointer to an affine transformation matrix, or `NULL` if no transformation is needed. If specified, Core Graphics applies the transformation to the arc before it is added to the path.

`x`

The x-coordinate of the center point of the arc.

`y`

The y-coordinate of the center point of the arc.

`radius`

The radius of the arc.

`startAngle`

The angle (in radians) that determines the starting point of the arc, measured from the x-axis in the current user space.

`delta`

The distance the arc should travel (in radians). A positive value indicates a counter-clockwise arc in the current user space.

## Discussion

The angle to the second endpoint of the arc is calculated by adding the delta to the start angle.

---

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