初一数学课时作业答案

1. D是BC的中点, BD = 1 cm, AD = AB + BD = 1 + 1 = 2 cm
2. BD = CD + BC
CE = CD + DE
BE = BC + CD + DE
BD = AD - AB = BE - DE
3. 平角=180°, 15° = 1/12 平角
周角=360°, 3/8周角 = 360 * 3/8 = 135°
1° = 60', 25°15′=25.25°
12. (1) AB > CD
(2) AB = CD
(3) AB < CD
14. 如BC在A的同一侧, AD = AB/2 = 8, AE = AC/2 = 20, DE = AE - AD = 20 - 8 = 12 cm
如BC在A的两侧, AD = AB/2 = 8, AE = AC/2 = 20, DE = AE + AD = 20 + 8 = 28 cm
.

1 . 2
2. BC CD+DE CD AB DE
3. 16分之1 135 25.35°
12. ＞ ＝ ＜
14. D是AB中点 所以AD=8cm
E是AC的中点 所以AE=20cm
DE=AE-AD=12cm

初一数学上册课时作业109页11题如答案?

1，1.5cm
2，BC;CD+DE; CD;AB;DE
3,1/6;135;
4,小于；等于；大于
5,12