(20S and 21S) Triangle Program
06-03-2017, 06:29 PM (This post was last modified: 06-15-2017 01:17 PM by Gene.)
Post: #1
 Eddie W. Shore Senior Member Posts: 1,198 Joined: Dec 2013
(20S and 21S) Triangle Program
Given three Cartesian coordinates, through points (R1, R4), (R2, R5), and (R3, R6), this program calculates:

1. The lengths of each side, represented by R7, R8, and R9.

2. The angle between lines connected by (R1, R4)-(R2, R5) and (R2, R5)-(R3, R6). The angle is stored in R0.

3. The area of the triangle. This is the final results shown.

[see diagram below]

The keystrokes for the HP 20S and HP 21S in this program are the same. Store the coordinates in variables R1 through R6, then press XEQ A.

HP 20S and HP 21S Program: Triangle Program
Code:
 STEP    CODE    KEY 01    61, 41, A    LBL A 02    22, 1    RCL 1 03    65    - 04    22, 2    RCL 2 05    31    INPUT 06    22, 4    RCL 4 07    65    - 08    22, 5    RCL 5 09    51, 21    >P 10    51, 31    SWAP 12    26    R/S 13    71    [ C ] Clear 14    22, 2    RCL 2 15    65    - 16    22, 3    RCL 3 17    31    INPUT 18    22, 5    RCL 5 19    65    - 20    22, 6    RCL 6 21    51, 21    >P 22    51, 31    SWAP 23    21, 8    STO 8 24    26    R/S 25    71     [ C ] (Clear) 26    22, 1    RCL 1 27    65    - 28    22, 3    RCL 3 29    31    INPUT 30    22, 4    RCL 4 31    65    - 32    22, 6    RCL 6 33    51, 21    >P 34    51, 31    SWAP 35    21, 9    STO 9 36    26    R/S 37    71    [ C ] Clear 38    22, 8    RCL 8 39    51, 11    x^2 40    75    + 41    22, 9    RCL 9 42    51, 11    x^2 43    65    - 44    22, 7    RCL 7 45    51, 11    x^2 46    74    = 47    45    ÷  48    2    2 49    45    ÷ 50    22, 8    RCL 8 51    45    ÷  52    22, 9    RCL 9 53    74    = 54    51, 24    ACOS 55    21, 0    STO 0 56    26    R/S 57    23    SIN 58    55    * 59    22, 7    RCL 7 60    55    * 61    22, 8    RCL 8 62    45    ÷ 63    2    2 64    74    = 65    61, 26    RTN

Example:
Inputs:
(R1, R4) = (4, 8)
(R2, R5) = (2, 3)
(R3, R6) = (3, 10)

Outputs:
R7 = 5.3852
R8 = 7.0711
R9 = 2.2361
R0 = 34.6952°
Area = 10.8374

Attached File(s) Thumbnail(s)

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