Meridian passage from Ocean Theory

This is part of the RYA Ocean Theory course resulting in the RYA Ocean Yachtmaster Theory certificate.
Ocean theory is the final step in getting your navigation to a professional level. It's a great subject and loads of fun.

Noon sight for latitude.
Declination different names.
This animation includes all the scenarios for a meridian passage.

Click the reverse button to repeat.
The above animation proves all the previous examples plus latitude different name to declination.
All the formulas for noon sights for latitude are listed below.

Latitude different name to declination.
Latitude = ZD - Dec.

Latitude same name and greater than declination.
Latitude = ZD + Dec.

Latitude same name and less than declination.
Latitude = Dec - ZD.

Declination 0°
Latitude = ZD
Note the formulas down for future reference.