BC = b'c ', AC = a'B', angle B '= angle c, how to prove that triangle ABC is equal to triangle a'b'c' It's the specific steps It's not a reason

BC = b'c ', AC = a'B', angle B '= angle c, how to prove that triangle ABC is equal to triangle a'b'c' It's the specific steps It's not a reason

Edge (SAS)

Let ABC be an unequal real number, and prove that ax ^ 2 + 2bx + C = 0. BX ^ 2 + 2cx + a = 0, CX ^ 2 + 2A + B = 0, the three equations cannot have equal roots
How to prove that a + B + C is not equal to zero
They don't have equal roots
They share a root

Certification:
(why do we have to do it from the positive side? Consider doing it from the negative side, and the conclusion is correct.)
Counter evidence
Suppose that all three equations have equal real roots,
There is a discriminant
4b^2-4ac=0,
4c^2-4ab=0,
4a^2-4bc=0
Namely
b^2=ca,
c^2=ab,
a^2=bc
therefore
(a+b+c)^2
=a^2+b^2+c^2+2(ab+bc+ca)
(a-b)^2+(b-c)^2+(c-a)^2
=2(a^2+b^2+c^2)-2(ab+bc+ca)
=0
If and only if a = b = C
This is not equal to a, B and C
So the hypothesis doesn't hold,
The original proposition holds

What are the properties of Vandermonde determinant? If it is convenient, can you give an example to explain it?

For example:
|1 1 1 .1 |
|a1 a2 a3 .an |
|a1^2 a2^2 a3^a .an^2|
|....| = d
|....|
|....|
|a1^(n-1) a2^(n-1) a3^(n-1) ...an^(n-1)|
Such a determinant is the Vandermonde determinant, and the result is: II (AI AJ)
one

25 degrees 31 minutes 25 seconds + 32 degrees 48 minutes 37 seconds=
The results are expressed in degrees

25 degrees 31 minutes 25 seconds + 32 degrees 48 minutes 37 seconds = 57 degrees 79 minutes 62 seconds = 57 degrees 80 minutes 2 seconds
=58 degrees, 20 minutes, 2 seconds

Seek help from foreign trade PI translator
2、 Quality
1. It has passed the inspection by the entry exit inspection and Quarantine Bureau;
2. In line with the national standards issued by the Ministry;
3. Consistent with the final sealing sample of both parties;
3、 Packaging
1. The Seller shall use the packaging materials and methods specified in this contract to package the goods, and the resulting packaging expenses shall be borne by Party B (the buyer);
2. Packing material and method: export standard carton
4、 Delivery
1. The Seller shall deliver the goods to the place of goods: Ningbo according to the delivery date stipulated in this contract
2. The delivery place determined by the buyer is Ningbo, and the expenses shall be borne by Party B
5、 Payment for goods
L/C
7、 Destination port:

Second, the quality one, the Entry-Exit Inspection and Quarantine check; 2, in line with the state Department issued standards; 3. and finally closed kind; Third, the packaging 1, the seller should use this contract packaging materials and methods of packaging goods. Packaging costs arising from B (buyer) shoulder; 2, packing materials and methods : standard export carton. Fourth, one delivery, the seller under the contract agreement for delivery of goods to be delivered to Ningbo : 2. Ningbo delivery to the buyer to determine the cost borne by the B side. 5, the money to pay C 7 : Head to Hong Kong

Four out of nine times three out of eleven times nine equals () times () times () equals ()

12 out of 11

Given that X of tan2 is equal to 2, what is SiNx equal to? What is cosx equal to?

tanx=2tan(x/2)/[1-(tan(x/2))^2]=-4/3
sinx=4/5,cosx=-3/5
or sinx=-4/5,cosx=3/5

5.36 cycle - (7.2-1.28 * 2.5) / 11,

5.3636.-(7.2-1.28*2.5)/11
=5.3636. - (7.2-0.32 * 4 * 2.5) / 11 utilization 2.5 × 4 = 10
=5.3636.-（7.2-3.2）/11
=5.3636. - 4 / 11 there's no easy way
=5 4/11=0.3636.

The line L passing through e (1,1) and the ellipse X & # 178 / / 8 + Y & # 178 / / 4 = 1 intersect at two points a and B, and the line y = 1 / 2x passes through the midpoint m of the line AB to find the linear l equation?

Because m is on y = 1 / 2x, let m (2a, a) a (x1, Y1), B (X2, Y2) satisfy: X1 & # 178; + 2y1 & # 178; = 8 (1) x2 & # 178; + 2Y2 & # 178; = 8 (2) (1) - (2) get: (x1 & # 178; - x2 & # 178;) + 2 (Y1 & # 178;) = 0 (x1 + x2) (x1-x2) = - 2 (y

3x=18
If both sides of the equation are divided by the same number not equal to 0, the left and right sides are still equal. 3x / () = 18 / () x = ()

3 3 6