# ISegment.QueryCurvature Method

Finds curvature and unit vector starting at point on segment and directed to embedded circle center.

[Visual Basic .NET]
**Public Sub QueryCurvature ( _**
**ByVal** *DistanceAlongCurve*** As **Double, _
**ByVal** *asRatio*** As **Boolean, _
**ByRef** *curvature*** As **Double, _
**ByVal** *unitVector*** As **ILine _
**)**

[C#]
**public **void** QueryCurvature (**
double *DistanceAlongCurve,*
bool *asRatio,*
ref double *curvature,*
ref ILine *unitVector*
**);**

#### Description

Returns the curvature at a specified distance along the segment. The distance can be given explicitly or as a ratio of the entire length of the segment. The curvature is returned as a Line representing a directional unit vector (in the direction going from the From Point to the To Point) and a double representing the magnitude of the vector of curvature.

#### Remarks

The unit vector returned by QueryCurvature points toward the center of the circle that has the same first and second derivative at the queried point with a curvature value equal to 1 / Radius of that circle.

#### See Also

ISegment Interface