Determining the instantaneous distance to the moon by direct triangulation

Details of a method for obtaining the instantaneous distance from the earth to the moon to within 5% by direct triangulation are described. Line of sight unit vectors are calculated based on azimuth and zenith angle measurements of the moon made simultaneously with ordinary surveying theodolites from two known points on the surface of the earth. These unit vectors and the baseline distance between the two observation points, typically several thousand kilometres apart, are used to compute the earth-moon distance. Recommendations for college and high school physics classes are included.