7. Find the length of the pond shown at the right. 8. A triangular parcel of land has borders of lengths 55 meters, 85 meters, and 100 meters. Find the area of the parcel of land. 80 565 n 9. Find the component form and magnitude of the vector w that has initial point 480 ft (-8. - 12) and terminal point (4, 1). In Exercises 10-13, find (a) 2v + u, (b) u - 3v, and (c) 5u - v. B 10. u = (0, -4). v = (-2, -8) 11. u = (-2. -3). v = (-1. -10) Figure for 7 12. u = i- j, v = 6i + 9j 13. u = 21 + 3j. v = -i - 2j 14. Find a unit vector in the direction of v = 7i + 4j. 15. Find the component form of the vector v with v = 12, in the same direction as u = (3. -5). 16. Forces with magnitudes of 250 pounds and 130 pounds act on an object at angles of 45" and -60", respectively, with the positive .r-axis. Find the direction and magnitude of the resultant of these forces. 17. Find the dot product of u = (-9, 4) and v = (1, 3). 18 Find the anole between the vectors i -7it iandy