ArcGIS Pro 2.8 API Reference Guide
Intersects Method (IGeometryEngine)
Example 

ArcGIS.Core.Geometry Namespace > IGeometryEngine Interface : Intersects Method
The base geometry.
The comparison geometry.
Returns true if geometry1 and geometry2 intersect.
Syntax
Function Intersects( _
   ByVal geometry1 As Geometry, _
   ByVal geometry2 As Geometry _
) As Boolean

Parameters

geometry1
The base geometry.
geometry2
The comparison geometry.

Return Value

True if the two geometries intersect.
Exceptions
ExceptionDescription
Either geometry1 or geometry2 or both are null or empty.
The method is not implemented for GeometryBag.
Incompatible spatial references between the input geometries.
Remarks
Two geometries intersect if they have at least one point in common. Equivalent to not Disjoint.
Example
// determine intersection between two polylines

List<MapPoint> pts = new List<MapPoint>();
pts.Add(MapPointBuilder.CreateMapPoint(1.0, 1.0));
pts.Add(MapPointBuilder.CreateMapPoint(3.0, 3.0));
pts.Add(MapPointBuilder.CreateMapPoint(5.0, 1.0));

Polyline line1 = PolylineBuilder.CreatePolyline(pts);

List<MapPoint> pts2 = new List<MapPoint>();
pts2.Add(MapPointBuilder.CreateMapPoint(1.0, 3.0));
pts2.Add(MapPointBuilder.CreateMapPoint(3.0, 1.0));
pts2.Add(MapPointBuilder.CreateMapPoint(5.0, 3.0));

Polyline line2 = PolylineBuilder.CreatePolyline(pts2);

bool intersects = GeometryEngine.Instance.Intersects(line1, line2);    // intersects = true
Geometry g = GeometryEngine.Instance.Intersection(line1, line2, GeometryDimension.esriGeometry0Dimension);
Multipoint resultMultipoint = g as Multipoint;

// result is a multiPoint that intersects at (2,2) and (4,2)
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

IGeometryEngine Interface
IGeometryEngine Members