1 Solution: (1) AB/AC = BE/EC = 3: 5 Because AE is the bisector of an angle, AB = 60 cm and AC = 100 cm can be obtained from BC= 80cm, so BD = AB * BC/AC = 54cm(E to

(2)BEF =∠BCA+∠2 =∠ Abd +∠ 1=∠BFE.

2 solution: (1)∠MAD = ∠NAD and triangle MAD and triangle NAD are right triangles, so AM=AN.

(2)AM = AN=4CM

Solution 3: (2) Make a point A about the symmetry point of riverbank CD. Assume that the drinking water at point E on the riverbank CD is AE+EB = A 'e+EB >; =AB (the shortest straight line between two points) and because A'C = AC = BD, CE=EB means that E is the midpoint of CD.

(2) AE=500m, so the total distance = 1000m.