2. In the same plane, the positional relationship between two straight lines is only parallel and intersecting.
There are three straight lines on the same plane. If there are only two parallel lines, then these three straight lines should have two intersections?
4. On the clock face. The minute hand turns 6 degrees at 1 min and the hour hand turns 0.5 degrees at 1 min. When the clock shows 2: 15 minutes, the angle between the hour hand and the minute hand is 22.5 degrees.
5.90 -46 57'32''=89 59'60''-46 57'32''=43 2'28''
6. Three students from the same school, Xiao Ming, Xiao Wei and Xiao Hong, live in three communities (as shown in the picture). A, B and C are connected at three points, with AB=60CM. BC= 100CM。 They plan to share a car to send everyone to school, but due to lack of parking spaces, they plan to set up only three residential areas. Why?
- A - B - C
draw
Answer: it should be located at point B. No matter where it is located at point A and point C, the sum of the distances traveled by two students must be section A and C. Therefore, it is necessary to look at the distance traveled by students at point B to minimize the sum of the distances traveled by three students in the pedestrian lane. Obviously, the minimum travel distance of students at point B meets the requirements, that is, the stop point should be located at point B.
7. One class held a philatelic exhibition, with 24 more stamps than the average of 3 per person and 26 less than the average of 4 per person. The number of stamps on display in this class is X.
Then there is a solution of (x-24)/3=(x+26)/4 to get x= 174.
8. When the products are distributed in stores, the profit rate increases from m% to (m+6)%, because the purchase price is reduced by 5%, while the sales price remains unchanged. What is the value of m?
Set the purchase price to 1.
Price:1(1+m%) =1(1-5%) (1+(m+6)%)
The solution is m= 14.
9. If 2x and 2-x are reciprocal, then x=?
2x=-(2-x)
x=-2