People's Education Publishing House, Grade 7, Volume 2, Math Exercise Book, Chapter 5, Lesson 65438 +00 Propositions, Theorems and Proved Answers

Answer: [knowledge combing] 1, sentence topic conclusion

2. True proposition and false proposition

3. Theorem Theorem

Step 4 prove

[homework] 1, c

2、D

3. Conclusion of the topic

4.( 1) Title:? 1+? 2= 180?

Conclusion:? 1 and? 2 Complementarity

(2) Title: Two angles are complementary angles of the same angle Conclusion: These two angles are equal.

(3) Title: Two straight lines are parallel to the same straight line Conclusion: These two straight lines are parallel.

5.Mn。 AB internal dislocation angle is equal, two straight lines are parallel, EF AB is equal to complementary angle, and two propaganda lines are parallel. If both lines are parallel to the third line, then? These two straight lines are also parallel to each other.

[homework] 6, c

7. A.

8、①②④

9.( 1) Counterexample of pseudo-proposition: If the number 9 is divisible by 3, it cannot be divisible by 6.

(2) True proposition

10, (1) If several angles are right angles, then they are all equal.

(2) If the last digit of an integer is 5, it can be divisible by 5.

(3) If a figure is a triangle, then the sum of its internal angles is 180?

(4) If two straight lines are perpendicular to the same straight line, the two straight lines are parallel to each other.

1 1, the answer is not unique, such as the condition: ② ③,

Conclusion: ①∶AB//DE, B=? Cod.

∵ BC//EF，E=？ 4 Goode. B=？ E