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54 lines
2.0 KiB
C++
54 lines
2.0 KiB
C++
/*This is a C++ Program to check whether point lies above, below or on the line. For any point t (xt, yt) on the plane, its position with respect to the line L connecting p and q is found by calculating the scalar s:
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s = A xt + B yt + C
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If s < 0, t lies in the clockwise halfplane of L; if s > 0, t lies on the counter-clockwise halfplane; if s = 0, t lies on L.
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For example, the equation of the line connecting points (2, 2) and (4, 5) is -3x + 2y + 2 = 0. The point (6, 3) lies in the clockwise halfplane of this line, because (-3)(6) + (2)(3) + 2 = -10. Conversely, the point (0, 5) lies in the other halfplane as (-3)(0) +(2)(5) +2 = 12.*/
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#include<time.h>
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#include<stdlib.h>
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#include<iostream>
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#include<math.h>
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using namespace std;
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const int LOW = 0;
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const int HIGH = 10;
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int main(int argc, char **argv)
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{
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time_t seconds;
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time(&seconds);
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srand((unsigned int) seconds);
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int x1, x2, y1, y2;
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x1 = rand() % (HIGH - LOW + 1) + LOW;
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x2 = rand() % (HIGH - LOW + 1) + LOW;
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y1 = rand() % (HIGH - LOW + 1) + LOW;
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y2 = rand() % (HIGH - LOW + 1) + LOW;
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cout << "The Equation of the 1st line is : (" << (y2 - y1) << ")x+(" << (x1
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- x2) << ")y+(" << (x2 * y1 - x1 * y2) << ") = 0\n";
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int x, y;
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cout << "\nEnter the point:";
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cin >> x;
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cin >> y;
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int s = (y2 - y1) * x + (x1 - x2) * y + (x2 * y1 - x1 * y2);
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if (s < 0)
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cout << "The point lies below the line or left side of the line";
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else if (s > 0)
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cout << "The point lies above the line or right side of the line";
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else
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cout << "The point lies on the line";
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return 0;
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}
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/*
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The Equation of the 1st line is : (3)x+(0)y+(-3) = 0
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Enter the point:1 4
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The point lies on the line
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The Equation of the 1st line is : (5)x+(-1)y+(-25) = 0
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Enter the point:1 1
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The point lies below the line or left side of the line
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The Equation of the 1st line is : (-6)x+(8)y+(-24) = 0
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Enter the point:19 21
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The point lies above the line or right side of the line
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