When polar coordinates are transformed into rectangular coordinates, such as: x ^ 2 + y ^ 2 = x r^2=r*cosQ r=cosQ Why can we make an appointment with R? R > = 0 on both sides? If it is equal to 0, then we can make an appointment? r^2-r*cosQ=0 r(r-cosQ)=0 R = 0 or r-cosq = 0 Because r-cosq = 0 contains r = 0, it can be directly written as r-cosq = 0 Is that right? Is it wrong? R ^ 2 = R, can r be reduced in this case? R ^ 2 = R -- > R = 1 or r = 0; if R is reduced to r = 1, won't r = 0 be missing?

When polar coordinates are transformed into rectangular coordinates, such as: x ^ 2 + y ^ 2 = x r^2=r*cosQ r=cosQ Why can we make an appointment with R? R > = 0 on both sides? If it is equal to 0, then we can make an appointment? r^2-r*cosQ=0 r(r-cosQ)=0 R = 0 or r-cosq = 0 Because r-cosq = 0 contains r = 0, it can be directly written as r-cosq = 0 Is that right? Is it wrong? R ^ 2 = R, can r be reduced in this case? R ^ 2 = R -- > R = 1 or r = 0; if R is reduced to r = 1, won't r = 0 be missing?

When r = 0, any value of Q represents the origin
From the perspective of polynomial simplification, this reduction is not strict
But from the actual situation of polar coordinates, this result still does not exclude the origin,
That is to say, when r = 0, Q still has a solution
That is to say, there is no omission, so it can be simplified

Transformation between polar coordinates and rectangular coordinates
In polar coordinate system, given two points a (3, - π / 3), B (1,2 π / 3), find the distance between two points a and B. by the way, is the instantaneous clockwise direction of the polar coordinate system negative? Such as - π / 3 in the question. Also, please answer the interaction process of polar coordinates and rectangular coordinates (Note: even if it's copied). It's these three questions that I don't understand

Yes, clockwise direction is negative rectangular coordinate system, a (3cos (- π / 3), 3sin (- π / 3)) = (3 / 2, - 3 (radical 3) / 2) B (COS (2 π / 3), sin (2 π / 3)) = (- 1 / 2, radical 3 / 2) so (AB) ^ 2 = (3 / 2 + 1 / 2) ^ 2 + (- 3 (radical 3) / 2 - radical 3 / 2) ^ 2 = 4 + 12 = 16ab = 4 in polar coordinates

Rectangular coordinates to polar coordinates
If a is reflected in the x-axis to B, find the polar coordinates of B

First, a and B are symmetric about X axis, so the Cartesian coordinates of B can be easily obtained as (2 * sqrt (3), - 2). Next, B is expressed in polar coordinates. The length r = sqrt ((2 * sqrt (3)) ^ 2 + (- 2) ^ 2) = 4, and the angle between B and X axis is theta = arctan (- 2 / (2 * sqrt (3)) = - 30 °

It is known that a is a matrix of order 3, A1, A2, A3 are three-dimensional linearly independent column vectors, Aa1 = a1 + 2A3,
Next title
Aa2 = A2 + 2A3, aa3 = 2A1 + 2a2-a3, then the determinant | a | =?

A(a1,a2,a3)= (a1,a2,a3)K
K =
1 0 2
0 1 2
2 2 -1
So | a | A1, A2, A3 | = | A1, A2, A3 | K |
Since A1, A2, A3 are linearly independent, so | A1, A2, A3 ≠ 0
So | a | = | K | = - 1 - 4 - 4 = - 9

1-0.6x = 0.5

0.6x=1-0.5
0.6x=0.5
x=0.5/0.6
That is, x = 5 / 6

A group of rational numbers x1, X2, X3, x4, X5 arranged from small to large, in which each number is less than - 1,
Please use less than sign to connect the following numbers in descending order:
1,X1,－X2,X3,－X4．X5．

x1＜x3＜x5＜1＜-x4＜-x2

If the polynomial x ^ 4 + MX ^ 3 + nx-16 can be divided by (x-1) (X-2), find the value of M, n

Let x ^ 4 + MX ^ 3 + nx-16 = (x ^ 2 + ax + b) (x-1) (X-2) x ^ 4 + MX ^ 3 + nx-16 = (x ^ 2 + ax + b) (x-1) (X-2) = (x ^ 2 + ax + b) (x ^ 2-3x + 2) = x ^ 4 + (A-3) x ^ 3 + (2-3a + b) x ^ 2 + (2a-3b) x + 2B corresponding coefficients be equal, and the equations of M, N, a, B are obtained: A-3 = m2-3a + B = 02a-3b = N2

As shown in the figure, in △ ABC, ad is the median line on the side of BC, e is the midpoint of AD, connecting be and extending AC to point F, DG is the median line of △ BCF
Syndrome: EF = 1 / 3bE

Method 1: the triangle AEG is similar to the triangle ADC, and E is the midpoint of AD, so eg / DC = 1 / 2, so eg / BC = 1 / 4 2. The triangle EFG is similar to the triangle BFC, so Fe / FB = eg / BC = 1 / 4, so EF / be = 1 / 3 method 2

Compare the power of 99 to the power of 9 / 9 with the power of 66 to the power of 9 / 6

The 9th power of 99 / the 99th power of 9 = (9 × 11) ^ 9 / (9 ^ 9) ^ 11 = 11 ^ 9 / (9 ^ 9) ^ 10
The 9th power of 66 / the 66th power of 6 = (6 × 11) ^ 9 / (6 ^ 6) ^ 11 = 11 ^ 9 / (6 ^ 6) ^ 10
Because (9 ^ 9) ^ 10 > (6 ^ 6) ^ 10
So 11 ^ 9 / (9 ^ 9) ^ 10

A 250KW three-phase transformer is equipped with 120 square meters of cables. Does this 120 square meters mean that the cross-sectional area of a single cable is 120, or the sum of three cables is 120?

It definitely refers to the cross-sectional area of a single (phase) conductor (unit: square millimeter). There is no statement about the sum of multiple conductors at all!