M is the midpoint of BC.

BN=AC，BN‖AC

2 a.m.

BN‖AC

∠ABN+∠BAC= 180

∠BAC+∠FAH=360 -90 -90 = 180

ABN =∠ method

AB=AF，BN=AC=AH

△ ABN△ faher

AN=FH

2 a.m.

FH=2AM, get the license.