# `GSPath tangentAngle(atNodeIndex:side:)`

*Instance Method*

The tangent angle at a node index, or `nil` when no tangent can be determined.

## Declaration

```swift
func tangentAngle(atNodeIndex nodeIndex: Int, side: GSNode.Side) -> CGFloat?
```

## See Also

### Tangents

- [`GSPath tangentAngle(at:side:)`](/Core/GlyphsCore/GSPath/tangentAngle(at:side:)) — The tangent angle at a node, or `nil` when no tangent can be determined.
- [`GSPath unitVector(atNodeIndex:)`](/Core/GlyphsCore/GSPath/unitVector(atNodeIndex:)) — The tangent unit vector at a node index, or `nil` when no tangent can be determined.
- [`GSPath unitVector(atNodeIndex:side:)`](/Core/GlyphsCore/GSPath/unitVector(atNodeIndex:side:)) — The tangent unit vector at a node index, or `nil` when no tangent can be determined.