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Anonymous users2024-02-07It's all back. The lower horizontal line is the same length as the upper and lower horizontal lines. The left and right sides are empty and put together to form a circle) In this way, subtract the circle from the rectangle, first when it is a rectangle, subtract the two left and right semicircles.
What are the other questions above, ask me.
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Anonymous users2024-02-061) The diameter of the drum is 1 meter, the side of the drum is a circle, and the circumference is pi*1 (pi is pi, and the circumference is generally taken as that is, the drum rolls around and walks a circumference of meters, and after rolling for 20 weeks, it is multiplied by 20, that is, it is taken in meters.) The drum is 10 meters long, so the area it presses is 10* square meters. Generally, the problem of the area of this drum is to multiply the distance traveled by the drum by the length of the drum.
2) The title says to walk a distance, not how long, let's assume a distance, for example, 80 meters (in order to calculate 8*10=80), A walked 80 meters for 10 minutes, that is, he walked 8 meters per minute; B walks 80 meters in 8 minutes, which means that he walks 10 meters per minute. It's clear that B goes faster. The velocity ratio of A and B is just like the two speeds, 8:
10=4:5 or 8 10=4 5 (The previous assumption of distance is for your convenience, but it is not necessary in practice.) )
3) If you have studied equations, it is easy to understand. Male teachers make up three-fifths of female teachers, and the remaining two-fifths of female teachers outnumber male teachers. Then using 20 (2 5) = 50, the number of female teachers is 50.
If you have a bad foundation, this question is more abstract, I hope you can understand it. If you really can't do it, just 40 people, 50 people try like this, and you can usually try the answer. Equation Solution:
Suppose there are x male teachers and y female teachers, and there are 20 more female teachers than male teachers, y-x=20;Male is two-fifths of female, x=y*(2 5) ("is" is the meaning of "equal", "of" is the meaning of "multiplication") If you list the equation in this way, you will not be able to solve it, and you can also try out the answer.
4) The circumference of the semicircle is the length of the half arc plus the length of the diameter (this should be understandable) Let the radius of the circle be r, the circumference of the circle is 2*pi*r, the length of the semi-circle arc is pi*r=, the length of the diameter is twice the length of the radius, which is 2*r, and the two add up to centimeters, so the radius is 10 centimeters. The area of the semicircle is half of the area of the whole circle, and the formula for the area of the circle is known, pi*r*r. That half of the area is pi*r*r 2.
157 square centimeters.
5) Connect the upper and lower lines, and the enclosed area is the area of the rectangle minus the area of the two semicircles. You should be able to understand this by drawing it yourself.
Study hard and wish you all the best in your exams tomorrow!
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Anonymous users2024-02-051. The circumference of the roller in the previous week is: *1 Forward 20 weeks: *20 Area: *20*10
2. Let the total distance be a meter, then the speed of A is a 10, and B is a 8 A: B = A 10: A 8 = 4:5
3. Suppose there are female teachers with a, then there are male teachers with a-20, then (a-20): a = 3 5 : 1 a = 50
4. Find the radius first, and then find the area of the whole circle, and divide by 2 to find the area of the semicircle.
5. Make up a rectangle, with the area of the rectangle - the area of the circle.
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Anonymous users2024-02-04First make up the above figure into a rectangle with a length of 5 and a width of 3, and then find the area of 3*5=15 square centimeters, and then look at the left and right semicircles as a whole circle, and subtract the area of the circle from the area of the rectangle!
The first question: the diameter is one meter, and the circumference of the drum is 1 meter * 314 = meters. Rolling for 20 weeks, it will advance to square meters of road compression.
The second question: the velocity of A: the velocity of B = one-tenth: one-eighth = 10:8 approx. = 5:4
This kind of question is still relatively easy to do, according to the meaning of the question, you can know the speed of A and B respectively (speed = distance time) with the speed of A compared to the speed of B, first list the formula, and then go to the denominator at the same time, and finally in the approximate minute, it is completed, don't forget to answer! (If you don't write the name of the unit and answer in the exam, you will be deducted points!) ）
Problem 3: You can set two unknowns!
Let x be the number of female teachers and y be the number of male teachers.
So we get x-y=20y=x3 5x=50y=30
If not, let it be an unknown:
Solution: There are x number of female teachers and three out of five male teachers.
x-3/5x=20
2/5x=20
x=20*5/2
x=50A: There are 50 female teachers in the school.
Generally, when you encounter this kind of problem, it is recommended that you list the equations!
Hope mine is helpful to you!
Good luck with your final exams tomorrow!
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