Mathematics wide angle in the fourth grade, and wide angle math problems in the first volume in the

Answer all the third questions.

Put it at the midpoint of bc I think the basis of this question is: the placed trash can is not required to be equal to the distance to a, b, c, d, but the sum of the distances from the four points of a, b, c, d to the trash can is the minimum, by the triangle side length relationship is easy to know that it should be established on the straight line where a, b, c, d is located, if placed between a and b, the distance from a to the trash can is reduced, but the distance from b, c, d three points to the trash can is increased, and it is easy to see that it is easy to see only when it is established at the midpoint of b and c, The sum of the distances from the four points to the trash can is minimal

BC midpoint, I don't believe the answer is so simple, but after thinking about it, it's an elementary school question after all.

Place it at the midpoint of BC, reason: if it is placed in the middle of AB or CD, then the two buildings in the opposite direction will have to go a long way!

This is the shortest math for applying vertical line segments.

(1) There are 15 + 14 + 13 + 12 = 54 people in the outermost layer.

2) Make use of enums: for example; There were 3 people standing on each side of the outermost layer, and 9 people in the entire phalanx; There were 4 men standing on each side of the outermost layer, and 16 men in the entire phalanx; There were 5 people standing on each side of the outermost layer, and there were 25 people in the entire phalanx... For example, when there are 15 people standing on each side of the outermost layer, the entire phalanx has 15*15=225 people.

Hope it helps. If you don't understand, you can hail me

How many students are in the outermost layer: 15-2 = 13 (students) 15 times 2 + 13 times 2 = 56 (students).

How many students are there in the whole phalanx: 15 times 15 = 225 (name).

A: There are 56 students in the outermost layer and 225 students in the entire phalanx.

But there is no picture? It would be nice if there was a picture.

Search online for teaching design and ppt. The main purpose is to train students to solve problems in real life.

Originally, it was supposed that the outermost number of people was 60, so there should be 60 4=15 people on each side. However, it should be noted that the landlord can see that the outermost layer of the square 1st side and the end of the 2nd side coincide, the 2nd side and the 3rd side coincide, the 3rd side and the 4th end coincide, and the 4th end and the 1st edge coincide. Therefore, the outermost 60 people of the phalanx are obtained after the original number of people on each side * 4 and then subtract 4, so the number of people on each side of the square is (60 + 4) 4 = 16 people, and the number of people in the square is 16 * 16 = 256 people.

If the landlord still does not understand the outermost layer of the square, he can draw the number of drawings by himself, and will find that the outermost number of layers of the square = the number of sides of the buy bar * 4 and subtract 4.

Let the bottom edge be x, and the two sides are x-2, and the equation is 2x 2 (x-2) 60 2x+2x-4=60 4x-4=60 4x=56 x=14 The phalanx has 14 into 14 196 people, and you are here to ask others to teach you, so to speak politely, where to give the score, and use "no, no points!! In that case, I don't want your "5" points, so I'll teach you for free.

It's not easy, 10+15=25 minutes, 25-24=1 minute, 24+1=25 minutes.

What kind of illogical question is this? And the speed gap between them is so big, a flashlight, then Yinyin can only pass one person at a time, so let the nuclear touch the one who runs fast run a few more times to send them, and the time should be:

A and B pass 3 minutes first.

B comes back with a flashlight for 3 minutes.

D with tension for the past 12 minutes.

A comes back for 1 minute.

5 minutes after A-C.

A comes back for 1 minute.

A and B have passed 3 minutes.

A total of 28 points. Haha, there are really smart people who change their hearts and talk about it, and support the 1st floor.

1.A and B go over, and then A comes back: 3+1 minute.

2.Ding and Zhang Zhang went to serve here, and B came back: 12+3 minutes.

3.A and scum C go over, A comes back: 5+1 minutes.

4.A and B pass, finish: 3 minutes.

The shortest total time is 28 minutes.

A and B pass 3 minutes first.

A comes back with a flashlight for 1 minute.

D with tension for the past 12 minutes.

B pantyhose laughs back for 3 minutes.

5 minutes after A-C.

A replied with 1 minute.

A and B have passed 3 minutes.

A total of 28 points. Not necessarily right.

While memorizing English words, getting dressed, tidying up the room, listening to **, then brushing your teeth, washing your face, and eating breakfast.

The time is 10 + 10 + 15 = 35 minutes.

1 It takes 3 minutes to get dressed, and 7 minutes to tidy up the room and memorize words at the same time. 2 It takes five minutes to brush your teeth and wash your face, and 10 minutes to eat breakfast and listen at the same time** so 10+10+5=25

1. It takes three minutes to get dressed, 7 minutes to tidy up the room, ten minutes to listen to **2, and five minutes to brush your teeth and wash your face.

3. Eat breakfast for 10 minutes and memorize English words for 10 minutes.

Through some simple examples in daily life, this unit allows students to try to find the optimal solution from the perspective of optimization, and initially experience the application of operations research ideas in practical life and the application of countermeasure theory in problem solving.

Example 1 discusses how to arrange the operation reasonably when making a pancake to save the most time, so that students can experience the application of optimization ideas in problem solving.

Example 2 uses the actual ingredients of the guests at home to make tea as the background, and asks "How to arrange so that the guests can drink tea as soon as possible?" ”

Example 3 is about queuing theory, which is a theory of random service systems, and one of the studies is how to minimize the waiting time of the service users.

Example 4 introduces the application of countermeasure theory from the story of "Tian Ji Horse Race", which studies the countermeasures that each side of the competition takes to defeat their opponents.

How to manage your time wisely?

1: How can I get my guests to eat pancakes as soon as possible?

2: How can I get my guests to drink tea as soon as possible?

3: How do you unload the ship so that everyone has the least waiting time?

4: Tian Ji horse racing anecdotes.

1: How can I get my guests to eat pancakes as soon as possible?

2: How can I get my guests to drink tea as soon as possible?

3: How do you unload the ship so that everyone has the least waiting time?

4: Tian Ji horse racing anecdotes.