(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.