According to the meaning of the question, DE⊥BF, AB⊥BF
Because ∠ DCE = 45
So ce = de = CD/√ 2 = 2/√ 2 = √ 2 (m)
Because "the shadow length of the 1m pole measured by the sun at a certain moment is 2m".
Therefore, according to the similarity principle, ef = 2de = 2 √ 2 (m) and BF = 2ab are obtained.
Because BC = 10 (m)
So BF = 10+3 √ 2 (m)
So ab = 5+3 √ 2/2 (m)
(If the approximate value is taken, AB≈7. 12(m))
Jiangsu Wu Yunchao wishes you academic progress.