In tetrahedral oabc, if edges OA, OB and OC are perpendicular to each other, and OA = 1, OB = 2, OC = 3, G is the center of gravity of triangle ABC, then the vector og * (OA + ob + OC) is?

Take o as the origin, OC, ob, OC as the coordinate axis to establish the space coordinate system, C (3,0,0), B (0,2,0), a (0,0,1), take the midpoint e of BC, connect OE, AE, e (3 / 2,1,0), vector OE = (3 / 2,1,0), △ ABC center of gravity on AE, | eg | = | EA | / 3, according to the formula of fixed score point, | eg | / | GA | = 1 / 2, λ = 1 / 2, set re

RELATED INFORMATIONS

1. Vector inner product operation | a | = 3. | B | = 4 = 60 ° to find (a + 2b). (a-b)
2. If the perimeter of RT △ ABC is 24 and the median length on its hypotenuse is 5, then the area of RT △ ABC is______ ．
3. Given x = log (2a) a, y = log (3a) 2a, prove 2 ^ 1-xy = 3 ^ y-xy. (PS: () is the base)
4. The distance from a point O to a vertex in an equilateral triangle ABC is 3, 4 and 5 respectively
5. Given the set a = {(x, y) / / X / + / Y / ≤ 1} B = {x, y) / X & # 178; + Y & # 178; ≤ 1}, what is the relationship between a and B
6. As shown in the figure, we know that the side length of the square ABCD is 1, P is the midpoint of the side of CD, and the point q is on the line BC, when BQ = 1___ Triangle ADP is similar to triangle QCP
7. As shown in the figure, given that the intersection point of graph of functions y = x + B and y = ax + 3 is p, then the solution set of inequality x + b > ax + 3 is () A. x＜1B. x＞1C. x≥1D. x≤1
8. As shown in the figure, in the quadrilateral ABCD, AC bisector angle bad, CE is perpendicular to point ab. if angle ADC plus angle ABC is equal to 180 degrees, ad plus AB is equal to 2ae AD + AB equals 2ae, and CD equals CB
9. Given vector a = (- 3,2,5) B = (1, - 3,0) C = (7, - 2,1) find | A-B + C | ^ 2 (| a | + | B | + | C |) ^ 2
10. How to apply parallelogram rule and triangle rule to calculation? Ask for help It's better to add a few examples to analyze. Please! If you answer well, you'll get bonus points
11. Given the vector a = (1, K) and the vector b = (9, K-5), if a is parallel to B, then the real number k is equal to?
12. As shown in the figure, ∠ ABC = 30 ° in △ ABC, take BC and AC as sides, make equilateral △ BCD and equilateral △ ace, connect be, and prove AB square + BC square = be square Such as the title
13. High school mathematics compulsory one of all the explanation? Thank you~
14. In triangle ABC, BD = CE, DF = EF, ab = AC
15. If we know that the sum of odd terms of an arithmetic sequence with even terms is 51, the sum of even terms is 60, and the first term is 1, then the general term formula is
16. Even term sum formula, odd term sum formula of arithmetic sequence Push to add result
17. The calculation formula of the sum of the first n even numbers
18. Sum of squares of even numbers within 100
19. Odd times even equals? Who knows. Know How to prove it
20. Use description method to express the solution set of the following set inequality with odd number, positive even number, x square + 1 less than or equal to 0 A set of few odd numbers