Answer: Pythagorean Theorem Pieces of Right Triangles is not a justification for the proof.
Explanation : Here,  is a right triangle with sides a, b and c. Perpendicular CD forms right triangles BDC and CDA.
 is a right triangle with sides a, b and c. Perpendicular CD forms right triangles BDC and CDA. 
CD measures h units, BD measures y units, DA measures x units.
Draw an altitude from point C to Line segment AB Let segment BC = a segment CA = b, segment AB = c,  segment CD = h,  segment DB = y, segment AD = x,
y + x = c	
a/c=y/a( Similarity theorem in triangles ABC and DBC )
 ------(1) (Cross Product Property)
------(1) (Cross Product Property)
Similarly,  (Similarity theorem in triangles ABC and ADC)---------(2)
 (Similarity theorem in triangles ABC and ADC)---------(2)
 (after adding equation (1) and (2) )
(after adding equation (1) and (2) )
 ( By additional property of equality)
( By additional property of equality)
 . ( because y + x=c)
. ( because y + x=c)
Thus, it has been proved that except Pythagorean Theorem Pieces of Right Triangles we use all other properties.