Here we will see how to find the vertex, focus directrix of a parabola using C or C++ program. To get these parameters we need the general equation of a parabola. The general formula is −
𝑦 = 𝑎𝑥2 + 𝑏𝑥 + 𝑐
The values of a, b and c are given.
The formula for the vertex −
The formula for the focus −
The formula for the Directrix - y −
Example
#include <bits/stdc++.h> using namespace std; void getParabolaDetails(float a, float b, float c) { cout << "The vertex: (" << (-b / (2 * a)) << ", " << (((4 * a * c) - (b * b)) / (4 * a)) << ")" << endl; cout << "The Focus: (" << (-b / (2 * a)) << ", " << (((4 * a * c) - (b * b) + 1) / (4 * a)) << ")" << endl; cout << "y-Directrix:" << c - ((b * b) + 1) * 4 * a << endl; } main() { float a = 10, b = 3, c = 4; getParabolaDetails(a, b, c); }
Output
The vertex: (-0.15, 3.775) The Focus: (-0.15, 3.8) y-Directrix:-396