(2)×

The second question, ∫≈ 1 and ∠4 are antipodal angles, ∠2 and ∠3 are antipodal angles.

∴∠ 1=∠4=60 ∠2=∠3= 180—60= 120

∠2= 120 ∠3= 120 ∠4=60

The third question, ∫≈ 1 and ∠3 are diagonal.

∴∠ 1=∠3=26

∵AB⊥CD

∴∠4=90∠2 =∠cob—∠ 1 = 90—26 = 64

∠2=64 ,∠3=26 ,∠4=90

The fourth problem, drawing problem (solve it yourself. )

The fifth problem is also the drawing problem. )

The sixth question, (1) ∠ dab = ∠1+90 = 30+90 =120.

∠DAB+∠B= 120+60= 180

(2) parallel. The reason (solve it yourself. )

The seventh question, (1) is ok.

(2) Let ∠1= y.

∠∠5 and ∠ 1 are congruent angles ∠3 and ∠ 1 are antipodal angles ∠ 1 and ∠2 are adjacent complementary angles ∠/kloc-.

∴∠ 1=∠5=y∠ 1 =∠3 = y∠2 = 180—— 1 = 180—y∠4 = 180—— 1 = 180—y

∫∠7 and ∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣

∴∠7=∠5=y∠6 = 180——5 = 180—y∠8 = 180——5 = 180—y∠ 1 = y∠2 = 180—y∠3 = y∠4 = 180—y∠5 = y∠6 = 6

Question 8, (1)B

(2) Answer

Question 9: Think about it (solve it yourself. )

The tenth question, (1) is another drawing question (solve it by yourself. )

(2) Do it yourself (solve it yourself. )

(3) Do it yourself (solve it yourself. )

Do it yourself (solve it yourself). )

Question 12, (1) Proposition: When the sum of two angles is equal to a flat angle, the conclusion is that the two angles are complementary. True proposition.

(2) Proposition: Isoangle is, and conclusion: Diagonal. False proposition.

Counterexample: If the two lines are parallel, the internal dislocation angles are equal.

(3) Proposition: Two parallel lines are cut by the third line, and the conclusion is that the internal dislocation angles are equal. True proposition.

Question 13, you can write it yourself. )

Question 14, (1) is yes.

(2) that I really can't write.