2.22.5
1. When the area around the rectangle is the largest square, the square enclosed by 100CM has 25CM sides and 625CM area? , that is, the maximum area of a rectangle surrounded by 100CM metal wire is 625CM? , so 800CM? It is out of the question.
The specific calculation process is as follows:
Let the two sides of a rectangle be A and B, respectively, with an area of S.
∫S = ab ≤( a+b)？ /4≤2500/4=625cm？ ≤800cm？
∴ Selected (D)
Connecting BD
BD = AC = BE
∴∠BDE=∠BED= 1/2(∠ABD)
∫∠ABD = 45
∴∠BED=45 /2=22.5
That is, the angle e is 22.5.
Hard work, score points, hee hee.