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B