A. Proof: (I guess if you want to write in English, I will use Chinese) because ab=ac, bap= cap, ap=ap.

So triangle bap= triangle cap, so bp=cp, angle dbp= angle ecp, angle dpb= angle epc.

So triangle dbp= triangle ecp (angle). So dp=pe Because angle apb= angle apc and angle apd= angle ape, angle qpd= angle qpe.

(Angle apb- Angle dpb= Angle apc- Angle epc) Similarly, triangle dpq= triangle epq, so similarly, triangle adq= triangle aeq, isosceles triangle ade, the connecting line from the midpoint of the bottom is high, so aq is perpendicular to de.

B.it has been proved.