This program is Copyright © 1975 by HewlettPackard and is used here by permission. This program was originally published in "HP55 Mathematics Programs".
This program is supplied without representation or warranty of any kind. HewlettPackard Company and The Museum of HP Calculators therefore assume no responsibility and shall have no liability, consequential or otherwise, of any kind arising from the use of this program material or any part thereof.
Given three sides of a triangle this program solves the triangle for the remaining parameters by the following formulas:
C =
cos^{1}((a^{2}+b^{2}c^{2})/2ab)
B = sin^{1}(b*sin(C)/c)
A = sin^{1}(a*sin(C)/c)
Reletter if necessary to make c the largest side. The program works in any angular mode. However, if in degree mode decimal degrees are assumed.
Step 
Instructions 
Input Data/Units 
Keys 
Output Data/Units 
1 
Enter program 

2 
Store a, b, and c (c is the largest) 
a 
STO 1 

b 
STO 2 




c 
STO 3 

3 
Find the solution 

BST R/S 
C* 



R/S 
B* 

R/S 
A 


* The stack must be maintained 




at these positions. 



Given the following three sides:
a = 30.3
b = 40.4
c = 62.6
Solve the triangle.
Solution:
C= 123.99°
B = 32.35°
A= 23.66°
LINE CODE KEYS 00. 01. 34 RCL 02. 01 1 03. 41 ENTER 04. 71 x 05. 34 RCL 06. 02 2 07. 41 ENTER 08. 71 x 09. 61 + 10. 34 RCL 11. 03 3 12. 41 ENTER 13. 71 x 14. 51  15. 34 RCL 16. 01 1 17. 34 RCL 18. 02 2 19. 71 x 20. 02 2 21. 71 x 22. 81 ÷ 23. 32 g 24. 13 cos^{1} 25. 84 R/S 26. 31 f 27. 12 sin 28. 34 RCL 29. 03 3 30. 81 ÷ 31. 34 RCL 32. 02 2 33. 22 x<>y 34. 71 x 35. 31 f 36. 34 LAST X 37. 22 x<>y 38. 32 g 39. 12 sin^{1} 40. 84 R/S 41. 23 roll dn 42. 34 RCL 43. 01 1 44. 71 x 45. 32 g 46. 12 sin^{1} 47. 00 GTO 00
R1 a R2 b R3 c
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