User:Michael Hardy/Hadley

In plane geometry, Hadley's theorem, asserted by Norman Wildberger to have been proved by Frank Hadley in 1980, states that in a triangle with an obtuse angle at B, in which in which the acute angle at C is two thirds the complement of the acute angle at A, with opposite sides a, b, c, we have


 * $$ b^2 = c^2 + ab \, $$

or


 * $$ \frac{b}{c} = \frac{c}{b - a}. $$

Some Pythagoras-related things:

 * Pythagoras' theorem
 * Pythagorean triple
 * Pythagorean trigonometric identity
 * Dulcarnon
 * Kātyāyana
 * Nonhypotenuse number
 * Parallelogram law
 * Treatment of Pythagoras' theorem in rational trigonometry
 * Synthetic geometry
 * Triangle
 * Pythagorean expectation
 * Ptolemy's theorem