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Jucimar_C
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Finding the function

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Hi,

How can I find the equation of a segment given by 2 points? Example: a(8,5) and b(5,8)
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Joe_Horn
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@Jucimar_C wrote:
Hi,

How can I find the equation of a segment given by 2 points? Example: a(8,5) and b(5,8)

Many methods.  Here's one that works great in CAS (not Home):

 

line((8,5),(5,8)) ---> y = -x+13

 

Be sure to type "line" in lowercase letters, or it won't work.

 

Here's a method that works in both Home and CAS:

 

simplify(lagrange([[5,8],[8,5]] ) ) ---> -x+13  (the "y=" is implied)

 

I hope one of these fits your needs.  Disclaimer: I don't work for HP. I'm just another Prime user.

-Joe-
Maké
Level 9
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Hi!, Josimar_C:

 

If you needed know, the conceptual theory, of find, one equation, see ...

 

a(x1, y1), b(x2, y2) ---> a(8,5), b(5,8)

 

y= mx + b

 

m= (y2 - y1)/(x2 - x1)

 

m=(8 - 5)/(5 - 8)= -3/3 = -1

 

m= -1( x1- y1) ---> m= -1 (8,5)

 

y - y1= m( x - x1)

 

y - 5= - (x - 😎

 

y - 5= - x + 8

 

Then, add 5 in (y-5) and 5 in (-x+8)

 

y-5+5=- x + 8 + 5

 

y= - x +13

Kind Regards !.
Have a nice day !.
@Maké (Technical Advisor Premium - HP Program Top Contributor).
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
Axel_59
Level 4
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On the HP50G, you can use DROITE. In RPL mode :

 

(8,5) (5,8) DROITE

 

 

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Tim_Wessman
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It took me 8 years to realize that was a french word... 🙂

TW

Although I work for the HP calculator group as a head developer of the HP Prime, the views and opinions I post here are my own.
Ciro_Bruno
Level 4
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Hello Jucimar

 

Let me suggest you a procedure to be performed in Geometry App. Please take a look at the attached sequence of screenshots. They are in Portuguese, but I guess it won't be a hard time for you

 

1st) Type both points in Symb view (GA and GB). Then create a line (GC) passing by GA and GB. You can go to Plot view and see how it looks like.

 

2nd) Go to Num view, choose and empty entry, click on Edit soft button ("Editar") and then in Vars. Select GC and you'll see the line's equation. Check the box if you want to see the equation further in Plot view.

 

Now, you can move the points and you'll see the chance in the line and its equation.

 

Regards,

Ciro

 

1 create points and line1 create points and line2 how they look like2 how they look like3 Num - edit entry3 Num - edit entry4 place the line referrence4 place the line referrence5 check the box for Plot view5 check the box for Plot view6 equation in Plot view6 equation in Plot view

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