## Sunday, August 13, 2017

### Casio fx-3650p and HP 21S: The Intersection Point of a Quadrilateral

Casio fx-3650p and HP 21S: The Intersection Point of a Quadrilateral

Introduction

This program calculates the coordinates of the center of quadrilateral.  For the derivation, please see this link:  http://edspi31415.blogspot.com/2017/08/geometry-intersection-point-of.html

Casio fx-3650P

See the diagram below.

Due to the lack of variable available, 7, the program asks for A, B, C, and D twice.  Most of my programs asks for the inputs, then executes calculations.  This program asks for some inputs, does some calculations, then asks for more input, then executes calculations, including replacing variables to make room for further calculations.

Program (91 steps):

? → A : ? → B : ? → C : ? → D :
(D – B) ÷ (C – A → X :
B – A X → Y :
? → A : ? → B : ? → C : ? → D :
(D – B) ÷ (C – A → C :
B – A C → D :
(D – Y) ÷ (X – C → X
D + C X → Y

HP 21S

See the diagram below.  Input the following points into R0 through R7.

Program (the code and steps should be the same for the HP 20S):

 Step Code Key 01 61, 41, A LBL A 02 33 ( 03 22, 3 RCL 3 04 65 - 05 22, 1 RCL 1 06 34 ) 07 45 ÷ 08 33 ( 09 22, 2 RCL 2 10 65 - 11 22, 0 RCL 0 12 74 = 13 21, 8 RCL 8 14 55 * 15 22, 0 RCL 0 16 32 +/- 17 75 + 18 22, 1 RCL 1 19 74 = 20 21, 0 STO 9 21 33 ( 22 22, 7 RCL 7 23 65 - 24 22, 5 RCL 5 25 34 ) 26 45 ÷ 27 33 ( 28 22, 6 RCL 6 29 65 - 30 22, 4 RCL 4 31 34 ) 32 74 = 33 21, 6 STO 6 34 55 * 35 22, 4 RCL 4 36 32 +/- 37 75 + 38 22, 5 RCL 5 39 74 = 40 21, 7 STO 7 41 33 ( 42 22, 7 RCL 7 43 65 - 44 22, 9 RCL 9 45 34 ) 46 45 ÷ 47 33 ( 48 22, 8 RCL 8 49 65 - 50 22, 6 RCL 6 51 74 = 52 21, 8 STO 8 53 26 R/S 54 55 * 55 22, 6 RCL 6 56 75 + 57 22, 7 RCL 7 58 74 = 59 21, 9 STO 9 60 61, 26 RTN

Variables – HP 21S:

 Register Input Output R0 A1 R1 B1 R2 C1 R3 D1 R4 A2 R5 B2 R6 C2 C’ R7 D2 D’ R8 X R9 Y

Example

From top-left hand corner clockwise:  (-1, 4), (4, 6), (5, -1), (0, 0)

Results:
X = 1.357142857
Y = 2.035714286

Eddie

This blog is property of Edward Shore, 2017.