It is known that am is the middle line of BC in triangle ABC AM^2=1/2(AB^2+AC^2)-BM^2

Let vector AB = a, vector AC = B, vector am = C, vector BM = D, extend am to d so that am = DM, connect BD and CD, then ABCD is a parallelogram, then vector a + B = 2C (a + b) square = 4C square a + 2Ab + b square = 4C square (1) vector B-A = 2D (B-A) square = 4D square a-square-2ab + b square = 4D square (2) (1) +

RELATED INFORMATIONS

1. If the vector a and B satisfy | a | = 2, | B | = 1, and a &; (a + b) = 3, then a, B =?
2. The function f (x) holds for all real numbers x and y, f (x + y) - f (y) = (x + 2Y + 1) x, and f (1) = 0, (1) find the value of F (0); (2) when 0 ≤ x ≤ 12, f (x) + 3 ＜ 2x + a holds, find the value range of real number a
3. Given that the function f (x) = (MX ^ 2 + 8x + n) / (x ^ 2 + 1) has a range of [1,9], X ∈ R, find the value of M and N?
4. The solution of the equations XY + x = 16 and xy-y = 8
5. (1 / 2) solving the system of linear equations with three variables {A-B + C = 0 4A + 2B + C = 3 2)
6. Let the right focus of hyperbola C: x24 − y2 = 1 be f and the line L pass through the point F. if the line L intersects both the left and right branches of hyperbola C, then the slope k of line L is () A. K ≤ − 12 or K ≥ 12b. K ＜ − 12 or K ＞ 12C. − 12 ＜ K ＜ 12D. − 12 ≤ K ≤ 12
7. If the sum of quadratic coefficient and constant term in the quadratic equation AX2 + BX + C = 0 is equal to the coefficient of the first term, then one root of the equation must be () A. 0B. 1C. -1D. ±1
8. It is known that the quadratic function y is equal to the square of x minus 2x plus 4. If there is only one intersection point between the line passing through the origin and the quadratic function, how many such lines are there What I want to ask is: why does this line have no intersection with the parabola when it happens to be the x-axis and y = 0?
9. How to calculate the net area of irregular figure
10. It is known that F 1 and F 2 are the focal points of the ellipse x 29 + y 25 = 1, the point P is on the ellipse and ∠ f 1pf 2 = π 3
11. Given the set M = {y | y = x & # 178; - 2x + 3}, n = {y | y = 2x & # 178; - 3x + 1}, then m ∪ n= Search process, online, etc
12. Ln (A / b) = LNA LNB ln (AB) = LNA + LNB, right?
13. In vector scalar product, why a ⊥ B a * b = 0
14. The nature of the inner, outer, center of gravity and perpendicularity of a triangle It's urgent
15. X (T) = 1-sint y (T) = cost
16. Axisymmetry is the relationship between two figures______ And______ The axisymmetric figure is a special shape______ .
17. According to the scale of 1:1000, the rectangle is 8cm in length and 5cm in width. If one tree is planted every 10m on the four sides of the fast ground, how many trees can be planted? Find the actual area first
18. 1 / 2, 1 / 3, 1 / 6, 1 / 2, 1 / 3, 1 / 6?
19. 1 / 1,2 / 1,1 / 2,3 / 1,2 / 2,1 / 3,4 / 1,3 / 2,2 / 3,1 / 4,..., according to the law, what is the 2010 term of this sequence Known sequence: 1 / 1,2 / 1,1 / 2,3 / 1,2 / 2,1 / 3,4 / 1,3 / 2,2 / 3,1 / 4,..., according to the law of its first ten terms, how much is the 2010 term of this sequence? It's better to have the process of solving the problem and the idea
20. What is the remainder of the 2002 number divided by 6