Cough, do me a favor, a math problem In △ ABC, ∠ BAC = 90 °, ∠ C = 30 ° ad ⊥ BC at D, be bisection ⊥ ABC intersects AC at point E, EF ⊥ BC at F, FM ⊥ AC at M

When EH is perpendicular to AD and foot drop is h, FD is parallel and equal to eh
Because be bisects the angle ABF, the angle EAB equals EFB equals 90 degrees, and EB is the common edge
So the triangle Abe is equal to the triangle AFE. So AE is equal to ef
Because the angle FME is equal to the angle EHA is a right angle, the angle MFE is equal to the angle AEH is equal to 30 degrees (see for yourself), and the MF is equal to eh
So the triangle AEH is equal to the triangle EFM, so EH is equal to FM, because EH is equal to fd
So MF equals FD
PS: because I didn't find the mathematical symbols in my mobile phone, I'm sorry

(1) Given the square root of 3x + 5y-a-2 + 2x + 3y-a = the square root of X + y-199 multiplied by the square root of 199-x-y, the value of a is obtained
(2) If 2 times the square root of A-1 + 3 times the square root of a + B + C - 4 times the square root of 1-A = 9, find the A-B power of (a-b)
(3) If 2 times (square root of X + square root of Y-1 + square root of Z-2) = x + y + Z, find the value of X, y, Z

(1) Because x + y-199 > = 0199-x-y > = 0, so, x + y = 199. Then, the square root of 3x + 5y-a-2 + 2x + 3y-a = 0,3x + 5y-a-2 = 0,2x + 3y-a = 0; X + y = 199 solution: a = 201. (2) from A-1 > = 0,1-a > = 0, a = 1. So, the root sign of 3 (a + B + C) = 9, (shouldn't there be C?) root sign (1

The fourth grade students go boating on the "May 1st" festival. If one boat is added, six people will sit in each boat. If one boat is reduced, nine people will sit in each boat. How many people will sit in the boat?

(6 × 2) △ 9-6, = 12 △ 3, = 4, 4 × 9 = 36. A: there are 36 people on board

A power supply bureau completes a rush repair task. The power supply bureau is 15 kilometers away from the rush repair site. The rush repair vehicle is loaded with the required materials. First, it starts from the power supply bureau. 15 minutes later, the electrician takes a jeep to start from the power supply bureau. As a result, they arrive at the rush repair site at the same time. It is known that the speed of the jeep is 1.5 times that of the rush repair vehicle

Suppose the speed of the emergency repair vehicle is x km / h, then 15x-151.5x = 1560. Solve the fractional equation and get x = 20. After testing, x = 20 is the solution of the original equation. Answer: the speed of the emergency repair vehicle is 20 km / h

The steps of solving practical problems with equations
Explain clearly

1. Find out the equivalent relationship;
2. Solve the unknowns;
3;
4. Solve the equation;
5. Checking calculation

① Wu Yong and Li Fang have 180 stamps in total. Wu Yong has three times as many stamps as Li Fang. How many stamps do Wu Yong and Li Fang have?
② An elephant weighs 10 times as much as a cow. A cow is 4.5 tons lighter than an elephant. How many tons does an elephant and a cow weigh?

If Li Fang has x stamps, Wu Yong has 3x
180=3x+x
x=45
A: Li Fang has 45 stamps and Wu Yong 135 stamps
If the cow weighs x tons, the elephant weighs 10x tons
10x=x+4.5
x=0.5
10 * 0.5 = 5 (ton)
A: cattle weigh 0.5 tons and elephants weigh 5 tons

Set up equations and solve practical problems
There are two greening groups. The first group planted 22 trees per hour on average. After 18 trees were planted, the second group began to plant trees, with an average of 30 trees per hour. How many hours after planting, did the second group plant the same number of trees as the first group?
A truck drives from a to B at the speed of 55 kilometers per hour. After the truck drives for 2 hours, a jeep also drives from a to B at the speed of 75 kilometers per hour. How many hours can the jeep catch up with the truck?
Car a goes from place a to place B at a speed of 60 kilometers per hour. After 180 kilometers, car B follows the same route. It is known that the speed of car B is 150 kilometers per hour. How many hours does it take to catch up with car B?
Three questions 15 minutes

30x = 18 + 22x8x = 18x = 18 △ 8x = 2.25 A: the number of trees planted in the second group is the same as that in the first group after 2.25 hours a: the jeep can catch up with the truck after X hours B: 55 × 2 + 55x = 75x20x = 110x = 5.5 A: the jeep can catch up with the truck after 5

A total of 120 people from the two groups go to a scenic spot. The scenic spot stipulates that groups with more than 80 people can buy group tickets. It is known that each group has a 20% discount over individual tickets. However, the number of both groups is less than 80. The two groups decide to buy group tickets together. The total discount is 480 yuan. How much is each group ticket?

Suppose X Yuan for each individual ticket, then x yuan for each group ticket (1-20%). When the two groups do not merge, the total cost is: 120x yuan; when the two groups merge, the total cost is: 120 (1-20%) x yuan; a total discount of 480 yuan is offered. The solution of 120x-120 (1-20%) x = 480 is: x = 20, (1-20%) x = 16 yuan. A: 16 yuan for each group ticket

Solving several equations to solve practical problems
Please mark the question number and process of each question, the fastest one is set as satisfactory answer, please
1: A walks 5 kilometers per hour, and B goes after a by bike two hours after starting
(1) If B's speed is 20 kilometers per hour, how many minutes does B catch up with a?
(2) If you ask Party B to catch up with Party A at 14 km, what's the speed of Party B?
2: A and B are 18 kilometers apart. After 1.5 hours of departure, B starts again. A is behind and B is in the same direction. A rides 8 kilometers per hour and B walks 5 kilometers per hour. How many hours does a start to catch up with B?
3: The fastest cyclist meets the slowest cyclist 35 minutes after starting. It is known that the speed of the slowest cyclist is five seventh of that of the fastest cyclist, and the speed of the fastest cyclist is 6 km around the city
4: A person has a sum of money in the bank with an annual interest rate of 1.98%. After saving for one year and deducting 20% of the interest, he gets 316.8 yuan of interest. How much money should he deposit in the bank one year ago?

X hours & nbsp; & nbsp; & nbsp; 20x = 5x + 5 * 2 & nbsp; & nbsp; X = 2 / 3 hours = 40 minutes, B's speed is v & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; V * (14-10) / 5 = 14 & nbsp; v = 17.5x hours & nbsp; & nbsp; & nbsp; & nbsp; 18 + 5x = 8x + 8 * 1.5 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp

Each of Party A and Party B processes 120 identical machine parts, and they start working at the same time. Party A processes 15 parts per hour, and Party B processes 12 parts per hour. When Party A completes the task, how many parts does Party B still have?
Ding Ding leaves home at 7:30 every morning and arrives at school at 7:50. Ding Ding has to delay arriving at school for 10 minutes a day. If he still leaves at 7:30, he has to walk 20 meters less than usual every minute. How far is Ding Ding's home from school?
A basket of apples weighs 56.5 kg. Divide the apples into three parts and put them in the original basket for three times. The first time they weigh 19.5 kg, the second time they weigh 24.5 kg and the third time they weigh 17.5 kg. How many kg do the basket and the apples weigh?
The distance between a and B is 360 km. The passenger cars and freight cars run opposite each other from a and B. the passenger cars run for one hour before the freight cars leave. The passenger cars run for 60 km per hour and the freight cars run for 40 km per hour. How many hours after the passenger cars leave, do they meet the freight cars? How far is the meeting place from B?

1. Suppose B has x left unfinished. 120 / 15 = (120-x) / 12 gives x = 242. Suppose Ding Ding's family is x meters away from school, X / 20-x / 30 = 20 gives x = 12003. Suppose the basket weight is XKG, then the apple weight is 56.5-xkg, 19.5 + 24.5 + 17.5-3x = 56.5-x, then x = 2.5, 56.5-x = 54, so the basket weight is 2.5kg, then the apple weight is 54K

Cough, do me a favor, a math problem In △ ABC, ∠ BAC = 90 °, ∠ C = 30 ° ad ⊥ BC at D, be bisection ⊥ ABC intersects AC at point E, EF ⊥ BC at F, FM ⊥ AC at M