It is known that the sine current I1 = 31.1sin (314T + 20 degrees) a, I2 = 10 times root sign 2Sin (314t-70 degrees) a Write their maximum, RMS, angular frequency, period, initial phase and phase difference, and draw the waveform Thank you first

It is known that the sine current I1 = 31.1sin (314T + 20 degrees) a, I2 = 10 times root sign 2Sin (314t-70 degrees) a Write their maximum, RMS, angular frequency, period, initial phase and phase difference, and draw the waveform Thank you first

i1
Maximum: 31.1a
Effective value: 31.1 / √ 2A
Angular frequency: 314
Period: 2 π / 314 ≈ 0.01s
Initial phase: 20 degrees
i2
Maximum: 10 √ 2A
Effective value: 10A
Angular frequency: 314
Period: 2 π / 314 ≈ 0.01s
Initial phase: - 70 degree
The phase difference between I1 and I2: 20 ° - (- 70 °) = 90 °

When ω t = 360 °, I1, I2 and I3 are?

I feel that:
When wt = 240, I1 = 240, and because 120 = i1-i2, I2 = 120, I3 = 0 degree
Sin240 is negative, sin120 is positive, sin0 is 0

Definition: if the square of a number is equal to - 1, it is recorded as I2 = - 1, and the number I is called an imaginary number unit. Then I1 = I, I2 = - 1, I3 = - I
i4=1,i5=i,i6=-1…… So i2011=_______

According to the numbers listed, it is found that the result of every four numbers is a cycle: I, - 1, - I, 1
2011 △ 4 = 502 + 3
So:
i2011=-i

How to prove that a matrix is invertible if and only if its determinant is not equal to 0
In proving its necessity, I met | AA ^ (- 1) | = 1, and then how to launch | a | a ^ (- 1) | = 1

Because | ab | = | a | B | ah, the nature of the book, Tongji fifth edition, page 40

Add addition, subtraction, multiplication and division in the middle to make it equal to 4 and 10

Add addition, subtraction, multiplication and division in the middle to make it equal to 4 and 10
7 7 ÷7－7=4；
(7 7－7)÷7=10.

Let the rank of a square matrix of order 5 be 3, then what is the rank of its adjoint matrix

In the title, the rank of a square matrix of order 5 is 3, which implies that there are two all zero rows. Then all the elements of his adjoint matrix are composed of his algebraic cofactors. At this time, it is not difficult to find that at least one row of their cofactors is 0, and all the algebraic cofactors are 0, So the rank of their adjoint matrix is 0. In fact, you just need to draw a 5-order square matrix with rank 3
1 1 1 1 1
1 1 1 1
1 1 1
0 0
0

After a number is reduced by 100 times, the current number is 45.54 less than the original number

Let the original number be X
x-(1-0.01)x=45.54
0.99x=45.54
x=46
A: the original number is 46

How many centimeters is an inch? How many centimeters is 24 inches multiplied by 16 inches

One inch is about 2.54cm

Xiao Ming read a story book. On the first day, he read 1 / 8 of the whole book, which is 21 pages more. On the second day, he read 1 / 6 of the whole book, which is six pages less. There are 172 pages left. How many pages are there in this story book?

172+21-6)÷(1-1/8-1/6)
=187÷17/24
=264 (page)

First simplify and then evaluate (6a ^ 2-25b ^) - 7ab-3 (ab-5b ^ 2 + 2A ^ 2), where a = 1, B = - 1

(6a^2-25b^)-7ab-3(ab-5b^2+2a^2)
=6a²-25b²-7ab-3ab+15b²-6a²
=-10b²-10ab
=-10b(a+b)
=-10b(1-1)
=0