## Saturday, June 3, 2017

### HP 20S and HP 21S: Triangle Program

HP 20S and HP 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.

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

 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

Eddie

This blog is property of Edward Shore, 2017