2. 1

3.60

4.30 90

5.∠E=60

6. 100

7.C

8.D

9.C

10. The internal angles of equilateral triangles are all equal and equal to 60.

An equilateral triangle with three lines in one

Equilateral equilateral angle

The outer angle of a triangle is equal to the sum of two non-adjacent inner angles.

Tails Equal angle

1 1.AD = DE = AE

∴∠ 1=∠2=60

∠∠BDE = 180，∠DEC= 180

∴∠4=∠5= 180 -60 = 120

AD = BD，AE = CE

∴∠6=∠7,∠8=∠9

∴∠6=∠8=30

∴∠BAC=∠6+∠ 1+∠8= 120

12. Omitted13.6 = = = = = = = = = = = = = = = = = = = = = = = = = =14.120.

Write it yourself. I have too much difficulty in typing. I'm going to do my homework, hehe