ArcGIS Pro 2.6 API Reference Guide
Inclination Property
Example 

ArcGIS.Core.Geometry Namespace > Coordinate3D Structure : Inclination Property
Gets the inclination of the Coordinate3D. The inclination is measured in radians.
Syntax
public double Inclination {get;}
Public ReadOnly Property Inclination As Double
Remarks
The inclination is the angle between the xy-plane and the Coordinate3D measured in the z-direction. The inclination is measured in radians and has a value between -PI/2 and PI/2 inclusive.

Coordinate3D

Example
Coordinate3D v = new Coordinate3D(0, 0, 7);
double inclination = v.Inclination;         // inclination = PI/2

v.SetComponents(-2, -3, 0);
inclination = v.Inclination;                // inclination = 0

v.SetComponents(0, 0, -2);
inclination = v.Inclination;                // inclination = -PI/2
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

Coordinate3D Structure
Coordinate3D Members