The first math problem in junior high school, kneel down to solve it, a good person has a safe life

Angle B = Angle C, proves: Because AD is parallel to BC, then angle 1 is equal to angle B, angle 2 is equal to role C, and because AD bisects angle EAC, so angle 1 is equal to angle 2, so angle B equals angle C

Equal. Because AD is parallel to BC

So angle b = angle 1 angle c = angle 2

And because AD bisects the angle EAC

So angle 1 = angle 2

So angle b = angle c

Angle B Angle C Proof :

AD parallel BC

Angle 1 Angle b (two straight lines are parallel, the isotopic angle is equal).

Angle 2 Angle C (same way).

and ad bisect angle EAC

Angle 1 Angle 2 (bisected angles equal).

i.e. angle b angle c

Because AD is parallel to BC, angle two is equal to angle C. One is equal to angle b. Because EB bisects the angle BAC. So b is equal to angle c.

Equal. Proof: Because AD bisects the angle EAC so angle 1 angle 2

And because AD BC can get angle 1 angle B angle 2 angle C

So the obtainable angle b angle c

Because AD bisects EAC, 1=2, and because 1=b, 2=c, b=c, b=c.

Stupid, the most basic ... You're probably useless.

The inner misalignment angle is equal to the isotope angle and the bisect is equal, so the angle b is equal to the angle c

Equal. Utilize isotope equivalence.

It's so simple, but someone answered, and it was useless for me to answer again.

Sales in February: a (1 + 10%) = 10,000 yuan).

In March, it was: 10,000 yuan).

Three-month total sales: a + 10,000 yuan).

When a=100, bring back the original formula: 10,000 yuan).

Hope it can help you o(o).

A 10,000 yuan = 1 million yuan in January, a 10,000 yuan = 1.1 million yuan in February (1 + 10%), a + (1 + 10%) a - (1 2) a = 1.6 million yuan in March.

Total sales in the first quarter = 100 + 110 + 160 = 3.7 million yuan.

January: 10,000 yuan; February: (1+10%)a=10,000 yuan; March: A+ (1+10%)A-A 2=10,000 yuan.

So the total for the first three months: a + 10,000 yuan).

When a = 100, substitution gets 370 (10,000 yuan).

Question 1 Let the purchase price be x, then there is x (1 + 30%) multiplied by the second question x discount, then there is 150 times x multiplied by 5% Question 3 Let the purchase price be x, then there is 900 times multiplied by 10% The fourth question assumes the cost of x, then there is (100-x) multiplied by 60 = (100--3x) multiplied by 72

Question 5 You are not clear about what is being asked, what is arranged?

Question 6 Let the mountain height be x, then there is (x-30 times 10) divided by 10=x divided by 15 I answer these questions not for your points, in fact, these questions are not difficult, but I don't want to do it, I have to be responsible for myself.

The main purpose of the application problem is to find the equation, find a quantity, and equal it, such as the first three questions: the money that I planned to buy and earn in the past will go through a discount = the last money now: the time A takes to climb the mountain after the first 30 minutes = the time used by B.

Let the purchase price of the commodity be x, then it can be obtained from the question: The solution of x=5000 is 100*5%=5 (100+5) 150= Therefore, this commodity is discounted by 7**.

If the purchase price of the commodity is x yuan, then 900* solution x = 700 If the cost of each set of desks and chairs is x yuan, then 60 * (100-x) = 72 * (100-3-x).

Let x people do it for two hours, 2x+8(x+5)=80*3 4 It took x minutes to set the armor, 10x=15(x-30) to solve x=90 The mountain is 900m

1. Set the purchase price to x, (x+. Solution x = 5000

2. 7% off. If the profit is 5%, the selling price is.

。Solution x=700

4、（100-x）*60=（97-x）*72。Solution x=825, let some people be x, 2x+(5+x)*8=80*3 4. Solution x=26, set B took x minutes, 10*30+10x=15x.

Solution x=60, then A took 60+30=90 minutes. The height of the mountain is 90*10=900 meters.

Willing to be a caring person, think seriously -

1.Let the purchase price be 80% x (1+30%)-x=200 x=5000, that is, the purchase price of this commodity is 5000 yuan.

2.If this commodity is based on the original price of x**, then 150x-100=100*5% x=70%, that is, this commodity is discounted by seven**.

3.Let the purchase price of the commodity be x yuan (90%*900-40)-x=10%x x=700, that is, the purchase price of this product is 700 yuan.

4.The cost of each set of desks and chairs is 60*(100-x)=72*(100-3-x) x=82, that is, the cost of each set of desks and chairs is 82 yuan.

5.Let's arrange x people to do it for 2 hours, and the workload per person per hour is 1 80 1 80*x*10+1 80*5*8=3*4, and the solution is x=2

That is, 2 people will do it for 2 hours, and then 5 people will do it for 8 hours.

6.Set time x minutes 10x=15(x-30) x=90 10x=900 That is, A took 90 minutes to climb the mountain, and the mountain is 900 meters high.

1. Set the purchase price x, xx130%x80%=200, x=? The following and so on, with the method of setting unknowns, very quickly.

Go to Jingyou online to check, there are detailed answers.

Well, it's really not easy, you have to think about it.

If it is 3:2, then enclose a rectangular chicken coop with an area of 60 square meters, the length is 3 10, the width is 2 10, the length of the fence is 3 10 + 2 2 10 = 7 10 = 4900 If it is 2:1, then enclose a rectangular chicken coop with an area of 60 square meters, the length is 2 30, the width is 30, the length of the fence is 2 30 + 2 30 = 3 30 = 2700< 4900, so 2:1 is more appropriate.

The long side is the wall.

Dad thinks the length and width are 3:2 and Mom thinks the length and width are 2:1 = 4:2

Therefore, the length of the 2:1 possession wall is large, which is more reasonable.

1.Plan to dig in ten days. So the original plan was to dig every day.

Because the construction was carried out one day first, and then four days earlier. Therefore, after changing the efficiency, the construction took a total of 10-1-4=5 days.

So after changing the efficiency, dig every day (

Fit: (2.)6 hours for A, 8 hours for B, and 12 hours for C.

So A injects 1 6. of the total amount of water per hour

B injects 1 8 of the total amount of water per hour

C discharges 1 12 of the total amount of water per hour

Because A and B open for two hours first, the remaining space in the pool is 1-7 12 for injection (1 6 + 1 8) * 2 = 7 12

In the end, A, B, and C started together, and it took a total of x hours.

1 8+1 6-1 12)*x=5 12 gives x=2

Combination: (1 6+1 8)*2+(1 8+1 6-1 12)*x=1 gives x=2

2. Set the water to 1 when it is full, and the pool can be filled only after opening the C pipe x hours.

2×（1/6+1/8）+1/12]x=1x=

1.Plan to dig in ten days. So the original plan was to dig every day.

Because the construction was carried out one day first, and then four days earlier. Therefore, after changing the efficiency, the construction took a total of 10-1-4=5 days.

So after changing the efficiency, dig every day (

Fit: (2.)6 hours for A, 8 hours for B, and 12 hours for C.

So A injects 1 6. of the total amount of water per hour

B injects 1 8 of the total amount of water per hour

C discharges 1 12 of the total amount of water per hour

Because A and B open for two hours first, the remaining space in the pool is injected (1 6 + 1 8) * 2 = 7 12.

In the end, A, B, and C started together, and it took a total of x hours.

1 8+1 6-1 12)*x=5 12 gives x=2

Combination: (1 6+1 8)*2+(1 8+1 6-1 12)*x=1 gives x=2