On weights and cords: real and potential angles
How the potential angle sits inside, outside, or upon the real angle formed by the cord's pendants
Under the heading 'On weights and cords' Leonardo notes that loads shift as the position of their supports changes, and continues an argument carried over from the foot of the previous discussion. The core of the page classifies the 'potential angle' by the real angle formed where the cord's pendants meet: within an acute real angle the potential angle lies inside as a semi-real angle, on a right angle the two coincide, and on an obtuse angle the potential angle falls wholly outside. An inverted triangular figure at the right, lettered a, b, c, d, illustrates the loaded cord and its angles.
On this page
Loads change with the position of their supports
A short marginal note picks up what was missing at the foot of the earlier passage: the weights change according to the changes of the sites at their supports. It links the loaded-cord analysis to the geometry that follows.
The potential angle inside the acute real angle
All real angles made at the junction of the pendants that are acute contain the potential angle within them: the semi-real angle a c d lies inside the acute real angle a b d. Any potential angle generated inside an acute real angle is therefore semi-real.
Right and obtuse cases of the real angle
When the potential angle is generated by a right real angle it lies neither inside nor outside, and the real angle serves as both real and potential, a mixed angle. When generated by an obtuse angle the potential angle is simply potential, falling wholly outside the real angle.