Picture a chair with 4 perfectly vertical legs joined at the top by a rail between each pair. The top face of each rail is a perfect 90-degree rectangle. If we lean each leg a few degrees towards the centre, the top face of each rail becomes a trapezoid with angles greater than 90-degrees at the 2 outside corners and less than 90-degrees at the 2 inside corners.
This creates a challenge for a chairmaker trying to create acurate joints. Is there a way to calculate the resultant angles (in the example shown 89.78 and 90.22 degrees) from a given splay angle (85 degrees in the example)?
