As shown in the figure, in rectangle ABCD, ab = 3, BC = 4, point P is the first moving point on diagonal AC, PE ⊥ pf intersects ad, AB with E and f respectively, proving: PE / PF = 3 / 4

As shown in the figure, in rectangle ABCD, ab = 3, BC = 4, point P is the first moving point on diagonal AC, PE ⊥ pf intersects ad, AB with E and f respectively, proving: PE / PF = 3 / 4

prove:
∵PE⊥PF
∴∠FPE+∠FAE=180°
The four points of a, F, P and E are concentric
∴∠FEP=∠FAP
∵AB∥DC
∴∠FAP=∠ACD
∴∠FEP=∠ACD
∵∠FPE=∠ADC=90°
∴⊿FPE∽⊿ADC
∴PE/PF=DC/AC=AB/BC=3/4
I hope you can adopt it with satisfaction and make progress in your study