MYSTERIES OF THE EQUILATERAL TRIANGLE - HIKARI Ltd

82 Applications
The ei are the projections of the cardiac vector onto the three sides of the
Einthoven Triangle and e1 − e2 + e3 = 0. Furthermore,
tanα = 2e2 − e1
√ =
3 2e3 + e1
e1
√ =
e1 3 e2 + e3
(e2 − e3) √ 3 ,
where α is the angle of inclination of the electrical axis of the heart. Along the
corresponding edge of the triangle, a point a distance ei (measured from the
EKG) from the midpoint is marked off. The perpendiculars emanating from
these three points meet at a point inside the triangle. The vector from the
center of the Einthoven Triangle to this point of intersection represents the
cardiac vector. Its angle of inclination is then easily read from the graphical
device shown in Figure 3.5(b).
Figure 3.6: Human Elbow [88]
Application 6 (Human Elbow). Three bony landmarks of the human elbow
- the medial epicondyle, the lateral epicondoyle, and the apex of the olecranon
- form an approximate equilateral triangle when the elbow is flexed 90 ◦ , and a
straight line when the elbow is in extension (Figure 3.6) [88].
Figure 3.7: Lagrange’s Equilateral Triangle Solution [171]