Question

1.如图①,一张直角三角形的纸片,像图中那样折叠,使两个锐角顶点A、B重合,若∠

Answer 1

1. 1

一张直角三角形的纸片,像图中那样折叠,使两个锐角顶点A、B重合

=> AE=BE, ∠BAD=∠B=30°, DE垂直于AB;

∠B=30°,AC=√3,

=> AB=2√3,

=> BE=√3 ,

=> DE=1

2. 3

AB//CD,

=> ∠ABE=∠BEC;

BF平分∠ABC交AD于F,

=> ∠ABE=∠EBC,

=> ∠EBC=∠BEC,

=> BC=CE,

BC=8,

=> CE=8;

CD=AB=5,

=> DE=CE-CD=3