X^2 + Y^2 = U^2 + V^2 (X>Y>0, U>V>0, 可以从比例关系得出)
XY = UV
X^2 + Y^2 + 2XY = U^2 + V^2 +2UV
X^2 + Y^2 - 2XY = U^2 + V^2 -2UV
(X+Y)^2 = (U+V)^2 =〉X+Y=U+V ( X+Y= -(U+V) 不应该考虑)
(X-Y)^2 = (U-V)^2 =〉X-Y=U-V ( X-Y= V-U 同样应该考虑)
1)当X-Y=U-V:简单加减:
2X=2U or X=U
2Y=2V or Y=V
1)当X-Y= V-U:简单加减:
2X=2V or X=V
2Y=2U or Y=U