Principles of Nature: towards a new visual language
© copyright 20032015 Wayne Roberts. All rights reserved.
Completing a scale structure of triangles:


Figure CET3 
For reasons similar to those given in the case of the Eutrigon theorem, Q,...can represent any coeutrigon, proving the theorem true for all coeutrigons. We may summarise this reasoning as follows:
The shape of any coeutrigon is specified by the ratio of its leg lengths, a/b. If we let the shorter of a eutrigon's legs be a, then the ratio a/b is always in the range 0 < a/b < (or equal to) 1. It can be seen from an examination of [the] figure ... that every ratio of a/b is possible in the diagram: a can be vanishing small or can be any value up to and including a = b. Thus every possible shape of coeutrigon can be accommodated in the diagram without altering the geometric relations, and thus the theorem holds true for all coeutrigons.
The geometric form of the Coeutrigon theorem states: the area of any coeutrigon (i.e. a triangle in which one angle is 120°) is equal to the area of the equilateral triangle on its hypotenuse ‘c’ minus the combined areas of the equilateral triangles on legs ‘a’ and ‘b’ [see figure CET1 above]. How can this be expressed algebraically, that is, as an equation?
Earlier we determined the area of an equilateral triangle in etu (which is simply p^{2} where p is the side length) but we have not yet determined the equation for the area of a coeutrigon in etu. However, there is a beautiful synchronicity with the equation for the eutrigon’s area which follows from a correspondence of the triangle altitudes between eutrigons and coeutrigons. This again reflects the complementary relationship between the two classes of triangle.
It is wellknown and easily proven that triangles of the same base and same altitude have the same area. This means that there is a surprising resonance between a eutrigon’s and coeutrigon’s areas —if legs a and b (i.e. the sides adjacent to the defining angle) are equal then it follows that they have the same area, namely their product, ab (as expressed in etu), [see figure below].
These two triangles have the same area because their bases and altitudes are the same.
We may demonstrate the complementarity of these triangles more clearly by placing them as [below],
Same triangles as above but here placed sidebyside to highlight their complementarity. The area of each triangle is identical when the bases b are equal and share the same 60° altitude a.
So the area of a coeutrigon expressed in etu is the same as for the corresponding eutrigon of the same respective leg lengths and thus simply the product of the coeutrigon’s leg lengths, ab.
We can therefore state the algebraic form of the Coeutrigon Theorem in terms of the new relative units of area (etu) as,
The area of a coeutrigon (given in etu) = ab = c^{2} – a^{2} – b^{2}
This follows from [Figure CET3] and the ‘area equation’, Q = C – A – B.
As with the Eutrigon theorem’s algebraic form discussed earlier, the Coeutrigon Theorem is also consistent with the Cosine Rule and is the same as that rule for the special case when angle C = 120°. ... Since 2CosC = 1, the Cosine Rule reduces to c^{2} = a^{2} + b^{2} + ab and, rearranging terms, we obtain the Coeutrigon theorem form above,
ab = c^{2} – a^{2} – b^{2}
Including the Pythagorean equation, we now have three Pythagoraslike equations and their corresponding geometric theorems (through the induction of relative units). Given that a and b are the sides adjacent to the defining angle (e.g. the 90° angle of a right triangle), and c is the hypotenuse or side opposite the defining angle, the three equations are:
These three equations and their associated geometric forms exactly correspond (via their respective stipulated internal angle) to the three regular polygons (equilateral triangle, square, and hexagon) which can uniformly tile the flat plane without gaps.
This then completes a scale structure of not only three algebraic theorems but of their corresponding resonant geometric theorems, and it is reasonable to conjecture, I feel, that when recognised and implemented as a complete scale structure within mathematical practice, and utilised in ‘resonant application’, that significant advances may follow in number theory and in our understanding of the foundations needed for a new visual language and music.
For example, the whole subdiscipline of trigonometry may now be reexamined in light of the new geometric understanding of the above equations (which includes the critical notion of relative units).
Number theory too is likely to be extended via the key of the relative unit, and will call into question the very foundations of number and the meaning of ‘integers’—of how they are written or represented, and of new operations, properties, and transformations that may now be discovered and made possible.
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