ArcGIS Pro 2.6 API Reference Guide
DotProduct Method
Example 

ArcGIS.Core.Geometry Namespace > Coordinate3D Structure : DotProduct Method
The input Coordinate3D to use in the dot product.
Calculates the dot product of this Coordinate3D and another Coordinate3D. Vector dot product is used.
Syntax
public double DotProduct( 
   Coordinate3D other
)
Public Function DotProduct( _
   ByVal other As Coordinate3D _
) As Double

Parameters

other
The input Coordinate3D to use in the dot product.

Return Value

A double representing the dot product of this Coordinate3D and the input Coordinate3D. The dot product is the sum of multiplying corresponding components of each Coordinate3D.
Example
// Easy 3D vectors
Coordinate3D v = new Coordinate3D(0, 1, 0);
// v.Magnitude = 1

Coordinate3D other = new Coordinate3D(-1, 0, 0);
// other.Magnitude = -1

double dotProduct = v.DotProduct(other);      // dotProduct = 0

Coordinate3D crossProduct = v.CrossProduct(other);
// crossProduct.X = 0
// crossProduct.Y = 0
// crossProduct.Z = 1

Coordinate3D addVector = v.AddCoordinate3D(other);
// addVector.X = -1
// addVector.Y = 1
// addVector.Z = 0

// Rotate around x-axis
Coordinate3D w = v;
w.Rotate(Math.PI, other);
// w.X = 0
// w.Y = -1
// w.Z = 0

w.Scale(0.5);
// w.X = 0
// w.Y = -0.5
// w.Z = 0

w.Scale(-4);
// w.X = 0
// ww.Y = 2
// w.Z = 0
// w.Magnitude = 2

w.Move(3, 2, 0);
// w.X = 3
// w.Y = 4
// w.Z = 0
// w.Magnitude = 5
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

Coordinate3D Structure
Coordinate3D Members