Joke Collection Website - News headlines - One morning, Xiao Zhang was walking to the experimental building AB. He found a giant steel bar put down from the top floor of the DC teaching building behind the experimental building.

One morning, Xiao Zhang was walking to the experimental building AB. He found a giant steel bar put down from the top floor of the DC teaching building behind the experimental building.

Solution:

Let Xiao Zhang have point E on his head and point F on his feet, and the CA extension line and DB extension line intersect at point G.

∵Rt△EFG∽Rt△ABG ∽Rt△CDG

∴CD/EF = DG/FG，①

AB/EF = BG/FG，②

①-②，(CD-AB)/EF = (DG-BG)/FG。

That is, (30-20)/ 1.6 = 30/FG.

The solution is FG= 4.8.

Substituting ① gives 30/ 1.6 = DG/4.8.

DG= 90 (m)

DF = DG -FG =90 -4.8 =85.2 (m)

A: If Xiao Zhang wants to see the slogan, he must be at least 85.2 meters away from the teaching building.