Exercises for Section 13.6 Evaluate the determinants in Exercises 1-10. 1. 2 . 2 1 0 3. 6 5 4. 10 0 12 10 17 5. 6. 2 2 4 NJWAN - AWE 7. 8. 1 - x - 1 1 - 1 - X 9. a b 10. a b C - b a Prove the identities in Exercises 11-14. 11. a b la b _c d (the two rows are interchanged). 12. a batc b+d (the last row is added to c d C d the first). 13. ra rb = d a b (the first row is multiplied by a constant). 14. a - sb b a b (a constant times the sec- c- sd d c d ond column is subtracted from the first). in Exercises 15-24(6) Let D and E be the points on the opposite sides of B and C, respectively, such that they generate perpendicular line segments as shown in the gure. Use vectors to prove that the ray XIV: crosses the segment BC in 90 angle. Do not use other facts about triangles; we can prove this using vectors only. C