TI-58/TI-59 Week: Law of Cosines
Introduction
[ A ]: stores either the angle θ or a
[ B ]: stores the length of side b
[ C ]: stores the length of side c
[ D ]: calculates the length of side a:
a^2 = b^2 + c^2 - 2 * b * c * cos θ
[ E ]: calculates the angle θ
cos θ = (b^2 + c^2 - a^2) / (2 * b * c)
The angle θ is opposite slot of side a.
Program Listing
000 76 LBL
001 11 A
002 42 STO
003 01 01
004 92 INV SBR (RTN)
005 76 LBL
006 12 B
007 42 STO
008 02 02
009 92 INV SBR
010 76 LBL
011 13 C
012 42 STO
013 03 03
014 92 INV SBR
015 76 LBL
016 14 D
017 43 RCL
018 02 02
019 33 x^2
020 85 +
021 43 RCL
022 03 03
023 33 x^2
024 75 -
025 02 2
026 65 ×
027 43 RCL
028 02 02
029 65 ×
030 43 RCL
031 03 03
032 65 ×
033 43 RCL
034 01 01
035 39 cos
036 95 =
037 34 √
038 42 STO
039 04 04
040 INV SBR
041 76 LBL
042 15 E
043 53 (
044 43 RCL
045 02 02
046 33 x^2
047 85 +
048 43 RCL
049 03 03
050 33 x^2
051 75 -
052 43 RCL
053 01 01
054 33 x^2
055 54 )
056 55 ÷
057 53 (
058 02 2
059 65 ×
060 43 RCL
061 02 02
062 65 ×
063 43 RCL
064 03 03
065 54 )
066 95 =
067 02 INV
068 39 cos (arccos)
069 42 STO
070 04 04
071 92 INV SBR
Examples
Calculating a:
Set the TI-58/TI-59 to Degrees mode:
Input:
50° [ A ]
45 [ B ] (b)
35 [ C ] (c)
[ D ] returns a: 35.00312885
85° [ A ]
100 [ B ] (b)
70 [ C ] (c)
[ D ] returns a: 116.9607609
Calculating θ:
52 [ A ] (a)
38 [ B ] (b)
49 [ C ] (c)
[ E ] returns θ: 72.15813198
80 [ A ] (a)
60 [ B ] (b)
65 [ C ] (c)
[ E ] returns θ: 79.47338145
Note: The next post will be on July 23, 2022.
Eddie
All original content copyright, © 2011-2022. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.
