The maximum value of sinusoidal voltage U is 311V, and the initial phase is negative 60. Find its instantaneous value analytical formula, and write out the instantaneous value when t = 0.0025

The maximum value of sinusoidal voltage U is 311V, and the initial phase is negative 60. Find its instantaneous value analytical formula, and write out the instantaneous value when t = 0.0025

Maximum: Um = 311 initial phase: φ = - 60 * 2 Π / 360 = - Π / 3 frequency: F = 50 (assumed) angular frequency: ω = 2 Π f = 100 Π u = um sin (ω T - Π / 3) = 311 sin (100 Π T - Π / 3) t = 0.0025 u = 311sin (100 Π * 0.002

Is the current and voltage of sinusoidal AC circuit measured by multimeter instantaneous value, maximum value or effective value? (2 points)

According to the principle of the multimeter, we can know that the AC current and voltage measured by the multimeter are effective values
Principle of measuring AC voltage: because the meter head is a DC meter, when measuring AC, it first goes through a parallel and series half wave rectifier circuit, rectifies AC into DC, and then passes through the meter head, so that AC can be measured according to the size of DC
The principle of measuring AC current is to convert AC current into DC current by using whole bridge

1-x of X-2 = 1-2 of 2-x, please,

It can be seen from the question that x ≠ 2
（1-x）（2-x）=（1-2）（x-2）
1-x=-1+2
x=0

It is known that the vertex of the parabola y = x & sup2; is C, and the line y = x + 2 intersects the parabola at two points a and B. try to find s △ ABC

Let the intersection of the line and the y-axis be m, then s △ ABC = s △ AMC + s △ MBC
C (0,0)
Simultaneous equations
y=x² （1）
y=x+2 （2）
We get x = - 1 or 2 and substitute (1) to get a (- 1,1) B (2,4)
For (2), another x = 0, then y = 2, so m (0,2)
S△ABC=S△AMC+S△MBC=1/2x2x1+1/2x2x2=3

Conversion of liquid density to gas density
What is the density of o-xylene at 0 ℃, 884.7kg/m3 at one atmospheric pressure, and how to calculate it

Divide it by its formula
(note unit conversion)

Mathematics of grade one in junior high school (square difference formula)
Using square difference formula to calculate
（x+3）（x-3）（x²+9）
（x+1/2）（x²+1/4）（x+1/2）
5908×60.2
40 and 2 / 3 × 39 and 1 / 3
There are no steps to follow
Inverse application of square difference formula
x²-25=（ ）（ ）
4m²-49=（ ）（ ）
-36y²+49x²=（ ）（ ）
-9a²+b²c²=（ ）（ ）

Don't make a mistake: (x + 3) (x-3) (X & sup2; + 9) = (X & sup2; - 9) (X & sup2; + 9) = x4-81 (x + 1 / 2) (X & sup2; + 1 / 4) (x-1 / 2) = (X & sup2; + 1 / 4) (X & sup2; - 1 / 4) = x4-1 / 1659.8 × 60.2 = (60-0.2) * (60 + 0.2) = 60 * 60-0.2 * 0.2 = 3600-0.04 = 3599...)

Let a and B be two points on the parabola X & #178; = 4Y, which are located on both sides of the y-axis, and f be the focus of the parabola. If | FA | = 2, | FB | = 5
Let a and B be two points on the parabola X & #178; = 4Y, which are located on both sides of the y-axis respectively, and f be the focus of the parabola. If | FA | = 2, | FB | = 5, the equation of the straight line AB is solved

A: parabola X & | 178; = 4Y = 2PY solution: P = 2 focus f (0,1), quasilinear y = - 1 according to the definition of parabola, we know that: when | FA | = Ya - (- 1) = 2, Ya = 1 | FB | = Yb - (- 1) = 5, Yb = 4A and B's ordinate values are 1 and 4Y = 1, X & # 178; = 4Y = 4, x = ± 2Y = 4, X & # 178; = 4Y = 16, x = ± 4A and B are on both sides of Y. 1) point a is

Is the weight and volume of water proportional

Yes, it is

Fill in the blanks in the multiplication table and observe carefully. What rules can you find?

This is an observation question, as long as the child can say one, for example
If you look at it vertically, the number in the first line is 1% larger than that in the top, the number in the second line is 2% larger than that in the top, the number in the third line is 3% larger than that in the top, and so on
Looking horizontally, you can also find the law

Given that the function f (x) = x2 + MX + LNX is a monotone increasing function, then the value range of M is ()

-2 √ 2 = 0, so m ^ 2-4 * 2 * 1