# 3D Trignometry problem - how to calculate the Horizontal distance?

• Apr 23rd 2012, 01:36 AM
colinwc
3D Trignometry problem - how to calculate the Horizontal distance?
Refer to the (very ordinary) 3d diagram below.

Formulae required to determine HD.

Slope Distance (SD), angles and dH are measureable.

A 3d soulition is required with no approximations, if possible.

Attachment 23693
• Apr 23rd 2012, 07:18 PM
colinwc
Re: 3D Trignometry problem - how to calculate the Horizontal distance?
Sorry one piece of information is missing; the azimuth of A'B' is also known.
• Apr 25th 2012, 09:06 AM
HallsofIvy
Re: 3D Trignometry problem - how to calculate the Horizontal distance?
It appears from your picture that ABB'A' is a parallelogram which means that AB and A'B' are the same length. Once you have that AB has length SD, which is given, and dH is given, it follows from the Pythagorean theorem that $HD= \sqrt{(SD)^2- (dH)^2}$.
• Apr 25th 2012, 05:59 PM
colinwc
Re: 3D Trignometry problem - how to calculate the Horizontal distance?
Unfortunately AB and A'B' are not the same length as the tilt angles at A and B are not equivalent.