In the triangle ABC, ab = AC, EF is the median line of the triangle ABC, intersecting AB, AC at e, f respectively, extending AB to D, making BD = AB, connecting CD

In the triangle ABC, ab = AC, EF is the median line of the triangle ABC, intersecting AB, AC at e, f respectively, extending AB to D, making BD = AB, connecting CD

Take the midpoint g of CD, connect BG, BFB as the midpoint of AD, G as the midpoint of AC, so BG is the median line of triangle ADC, then BG is parallel to ACB as the midpoint of AD, f is the midpoint of AC, so BF is the median line of triangle ADC, then BF is parallel to DC, so bfgc is a parallelogram, BF = GC angle, AEF = angle AFE, so angle bef = angle CFE, and because EF = Fe

Which is bigger, the 99th power of 9 or the 99th power of 99

9 to the 99th power
The third power of 9 is 729
The 33rd power of 729 is bigger than the 9th power of 99

1,11111 general term formula
What is the general formula of this sequence?

10 to the nth power and divide by 9

{4x-2y = 4, 2x-2y = 2},

4x-2y=4…………………… ①
2x+y=2…………………… ②
② X 2 - 1, where 4Y = 0
The solution is y = 0
Substituting ①, there are: 2x + 0 = 2
The solution is: x = 1
Therefore, the solutions of the equations are: x = 1, y = 0

What is the law of series and parallel circuit voltage

In a series circuit, the power supply voltage is equal to the sum of the voltages at both ends of each electrical appliance
That is, u = U1 + U2
The voltage in parallel circuit is equal everywhere
That is, u = U1 = U2

The result of fraction 1A + 1 + 1a (a + 1) is___ ．

The original formula is aa (a + 1) + 1a (a + 1) = a + 1a (a + 1) = 1a

What is the total luminous power of two "220 V 60 W" incandescent lamps connected in series in a home circuit?

There are several ways to solve problems. I'll give you one
The resistance of incandescent lamp r = u ^ 2 / P = 220 ^ 2 / 60 = 806.67 Ω can be obtained by 1220V 60W and P = u ^ 2 / R
2. The two lamps are connected in series in the family circuit, that is, under the voltage of 220 V, the total luminous power of the two lamps is PZ = u ^ 2 / 2R = 30 W

1.(a^2bc)^2÷(ab^2c） 2.｛（3a+b）^2-b^2}÷a
Thank！

1.(a^2bc)^2÷(ab^2c）
=a^4b^2c^2÷(ab^2c）
=a^3c
2.｛（3a+b）^2-b^2
=(9a^2+6ab)÷a
=9a+6b

The resistance of the consumer is 120 ohm, so that 1 / 5 of the total current in the circuit passes through the consumer, and a () ohm is connected in parallel with the consumer
The resistance of the consumer is 120 ohm. If 1 / 5 of the total current in the circuit passes through the consumer, a () ohm resistance is connected in parallel with the consumer. If the voltage at both ends of the consumer is one fifth of the total voltage, a () ohm resistance should be connected in series with the consumer

30 480

There are 10 6-meter-high cylindrical wooden columns in the school auditorium. The perimeter of the bottom surface of each column is 1.884 meters. How many square meters are the side areas of these columns?
If you want to paint the surface of these wooden columns, how much will it cost to calculate at 15 yuan per square meter?
I don't have much time to hand it in tomorrow. Please answer quickly,

Side area of each cylinder = 1.884 × 6 = 11.304 square meters
Side area of 10 columns = 10 × 11.304 = 113.04 square meters
The total amount of money needed = 15 × 113.04 = 1695.6 yuan