Exercise in class: 1, D 2, B 3. If two angles are equal, so are their complementary angles. 4. 1 false proposition 2 true proposition 3 false proposition

24.2 Proposition proof

1, a 2, is incorrect. When n=6, n-3n+7 = 25, and 25 is not a prime number. 3. It is known that two straight lines are parallel and the same angle is equal; The vertex angles are equal; Equivalent substitution.

24.3

1、B 2、B

24.4 Property Theorem of Parallel Lines

1，C 2，C 3。 If two angles are equal, they are acute angles 4 and 5.

Synchronous detection test questions

I. 1，B 2，A 3，C 4，B 5，A 6，C 7，B。

2. A triangle is equilateral if its three sides are equal.

10、30 1 1、 120 12、3 13、52 、 14、80 、

Innovation and improvement

1. 1，C 2，B，

Most of them are typed, and the title numbers are indicated. See for yourself. It's hard to type them out. ...