# Getting Points for Parabolas

By , 26 Jan 2009

## Introduction

Recently, I have been having a lot of algebra homework about graphing parabolas. It was a bit annoying doing the same process for all of my problems, so I decided to make a tool that will give me all the values I needed to graph:

• Vertex: Point where lines intersect
• Axis of symmetry: Line that will pass in the middle of the Parabola, in the X axis
• Y-intercept: Point where Y axis is intercepted, and X = 0
• Y-reflection: Another point to graph our Parabola

## The Code

This code is really basic code, integers and decimals handling, so I will explain it a little bit.

```decimal A = int.Parse(txt1.Text);
decimal B = int.Parse(txt2.Text);
decimal C = int.Parse(txt3.Text);
decimal X;
decimal Y;
decimal X_rf;
//Axis Of Sym Op
decimal Axis_Sym = -1 * B / (2 * A);
axis_sym.Text = Axis_Sym.ToString();
X = Axis_Sym;
//Vertex Op
Y = A * (X * X) + B * X + C;
vertex.Text = X + " , " + Y;
//Y-Intercept Op
y_int.Text = X + " , " + C;
//Y_Ref Op
X_rf = X + X;
y_ref.Text = X_rf + " , " + C; ```

The code gets `string `values from 3 textboxes in the form, it converts the `string `value to `decimal `using `Int.Parse(String)`. Once we have the decimal values (I used `decimal `in case the results of all the operations would come out as `decimal`s). I'll describe the formulas to get the required points.

• Axis of Symmetry: Here we find X  = `-(B) /  2 * A`
• Vertex: we need to get Y, so  Y = `A(X)2 + B(X) + C` so the vertex = (X, Y), a point in a coordinate plain.
• Y-Intercept : A point where X = 0, and the line touches Y axis = `(0, C)`
• Y-Reflection : Another point to graph our line = `( (X - X), C )`

So that's it. We are ready to graph all the points, Soon I will add the code that actually graphs the points in a coordinate plane.

## Points of Interest

This program was made by a 14 year old kid. This tool turned out to be really helpful.

## History

• 26th January, 2009: Initial post

 Prox-YD Software Developer (Senior) Prox-Young Developer Honduras Member
I started to code at the age of 12, with visual basic i made an advanced webbrowser called "BlueFlame", which won a computer fair in 2007, Then i moved to c#, but kept on with visual basic, started the "Prox" project at the age of 13 , meant to be an open source project, the project consists in :
Making good software, Good looking software.

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