已知线段AB=4cm,延长AB至点C,使BC= 1 2 AB,反向延长AB至D,使AD=AB(1)按题意画出图形,

2025-05-14 04:49:00
推荐回答(1个)
回答1:



(1)作图如上:①以B为圆心,2cm为半径,
画圆于AB的延长线交于点C,则BC=
1
2
AB=
1
2
×4=2cm.
②以A为圆心,4cm为半径,画圆于AB的反向延长线交于点D,则AD=AB=4cm.
CD=AD+AB+BC=4+4+2=10cm;

(2)EF=
1
2
AD+AB+
1
2
BC=
1
2
×4+4+
1
2
×2=7cm.