13.1 problem 17
13.2 problem 19
13.3 problem 20
13.4 problem 21
13.5 problem 22
13.6 problem 23
13.7 problem 24
13.8 problem 25
13.9 problem 26
13.10 problem 27
13.11 problem 28
13.12 problem 29
13.13 problem 30
13.14 problem 31
13.15 problem 32
13.16 problem 33
13.17 problem 34
13.18 problem 35
13.19 problem 36
13.20 problem 37
13.21 problem 38
13.22 problem 39
13.23 problem 40
13.24 problem 41
13.25 problem 42
13.26 problem 43
13.27 problem 44
13.28 problem 45
13.29 problem 46
13.30 problem 47
13.31 problem 48
13.32 problem 49
13.33 problem 50
13.34 problem 58
13.35 problem 59
13.36 problem 63 (a)
13.37 problem 63 (b)
13.38 problem 63 (c)
13.39 problem 67