i really need help with these practice question

6. If a . b = 6, then what is b . a equal to? a. O b. 7. Consider the diagram on the right, What is a vector that is opposite to AB a. C. ED b. DE d. AF 8. Consider the diagram on the right, u = AB, V = AD, and w = AE HC =? a. utw C. w - u b. -(u+w) d. u - w 9. For which a value will the vector (1, a, a+1) be perpendicular to the vector (-3, 1, a)? a. - 3 Ow b. P ! 10. A force of magnitude 5 N acts on an object. A second force of magnitude 7N acts at 50" to the other force. What is the magnitude of the resultant of these two forces? a. 8.60 N C. 11.60 N b. 10.91 N d. 12.00 N1. When two opposite vectors are added: a. The resultant is twice the original vector b. The resultant is a vector perpendicular to the vectors c. The resultant is the zero vector d. None of the above 2. A represents a vector of 100 km/h at N20'E. The vector - -A a. 20 km/h at N20 E 100 km/h at N20 E b. 20 km/h at $20'W 20 km/h at W20'S 3. AB is the vector from the point (1, 2) to the point (3, 4). Calculate the magnitude of this vector. C. V3 + 5 C. 8 d. 2 d. 2V2 4. a = (-6,3,3), b = (2,5, -3), and c = (0, 1, 4). Determine a + b - d. a. (-4, 9, 4) (4, -9, -4) b. (-4, 7, -4) (-4, -7, 4) 5. If [a| = 4, then |-2a| =? a. 8 b. -8