Given a sinusoidal AC current I = 10sin (314 + 3.14 / 3) a, the effective value, frequency and initial phase of the current are obtained

Given a sinusoidal AC current I = 10sin (314 + 3.14 / 3) a, the effective value, frequency and initial phase of the current are obtained

I = 10sin (314T + 3.14 / 3) a?
Effective value I = 10 / √ 2A
Frequency f = 314 / (2 π) = 50 Hz
Output phase P = 3.14 / 3 = 1.04 degree

How to measure the phase difference of two sinusoidal signals with the same frequency according to Lissajous figure method

When two signals with the same frequency are input into x and Y directions respectively, Lissajous figure can be generated
X=Acos(ωt)
Y=Bcot(t+φ)
T-parameter, the physical meaning is time
A-X direction signal amplitude
B-Y direction signal amplitude
ω - circular frequency, i.e. 1 / 2 π of signal frequency
φ - phase difference
It can be seen from the above parameter equation that if the phase difference is a straight line between the first and third quadrants and the phase difference is π, the graph is a straight line passing through the origin and the second and fourth quadrants, and if the phase difference is π / 2, the graph is a circle, For other phase differences, the figure is an ellipse between a circle and a straight line. Therefore, the phase difference can be roughly determined. If the figure is to be accurately obtained, it can only be derived from the above parameter formula after measurement. See the reference for details

Xiao Ming wants to use the electric energy meter to measure the electric power of the microwave oven at home. He observes that the electric energy meter is marked with 1600imp / kW · H (IMP means the number of flashes). When only the microwave oven is working in the circuit, the indicator light flashes 32 times in 1min, and the microwave oven consumes power in 1min______ KW · h, its electric power is______ W．

The power consumption of microwave oven is 321600kw · H = 0.02kw · h in 1min, and its electric power is p = wt = 0.02kw · h160h = 1.2kW = 1200W

Three mathematical problems, on the first equation of junior high school
1. A circular runway is 400 meters long. A travels 550 meters per minute and B 250 meters per minute. A and B set out in the same direction at the same time. How many minutes will they meet again?
2. A middle school organizes military training for Junior One students, and the base is allocated to several dormitories of the school. If there are 8 students in each dorm, there will be 12 beds less; if there are 9 students in each dorm, there will be 2 dormitories free. How many students will participate in the military training?
3. When a pair of passengers take a car, it is required that the number of passengers in each car is equal. At first, 22 people take a car, but one person is left behind. If one car leaves empty, then all passengers can ride on the other cars equally. It is known that each car can only hold 32 people at most. How many cars and how many passengers are there in the beginning?
Urgent >_

The first question: let them meet again after t minutes. According to the meaning of the question, when they meet again, it must be that a walks n more circles than B (that is, 400 meters more distance, n is a natural number). Then the equation can be listed: 550t = 250t + 400N. After optimization, 3T = 4N. When n = 1, t = 4 / 3 minutes, that is, 4 / 3 minutes later, a and B meet for the first time

If Sn = 48, s2n = 60, then s3n=______ ．

∵ sequence {an} is an equal ratio sequence, and its first n terms and Sn, s2n Sn, s3n-s2n also form an equal ratio sequence. ∵ (60-48) 2 = 48 × (s3n-60), the solution is s3n = 63, so the answer is 63

Write the solution of equations clearly
2=x+y ①
2x-3y+2z=5 ②
x+2y-z=3 ③

③ * formula 2:2x + 4y-2z = 6.4
② Formula + 4: 4x + y = 11.5
Formula 5 - ①: 3x = 9
x=3
Substituting: y = - 1
z=-2

As shown in Figure 2, the cross section of the dyke along the river is trapezoidal ABCD, the dam crest ad = 4, the dam height AE = 6, the slope AB, the slope ratio i = 1:2, and the angle c = 60 ° to calculate the length of the slope ABCD
I'm sorry. It should be the length of AB and CD

The vertex D of ladder ABCD is DF ⊥ BC in F
∫∫ B = 45 °∫ BAE = 45 °∫ be = AE = 6, and ab = 6 √ 2 can be obtained by Pythagorean theorem
∵∵ C = 60 °∵ FDC = 30 °∵ FC = & frac12; DC has Pythagorean theorem and DC = 4 √ 3
That is to say, the length of slope AB and CD is 6 √ 2,4 √ 3

9 = 19 how to fill in the operation symbols and brackets to make the equation hold

(9 × 9 + 9) ÷ 9 + 9 = 19

Let B be the adjoint matrix of the fourth-order square matrix A. if determinant A is equal to 1 / 2, what is the inverse matrix-2b of determinant (3a)?
I use the telephone type, some symbols are not easy to type, sorry

|(3A)^(-1)-2B|
=|A^(-1)/3-2B|
=|A*/(3|A|)-2A*|
=|-4A*/3|
=(-4/3)^4.|A*|
=(256/81)*(1/2)^3
=32/81

Four Sevens add, subtract, multiply and divide equal 10
How do you calculate it?

(77-7)/7=10