# Java Exercises: Test whether AB and CD are orthogonal or not

## Java Basic: Exercise-235 with Solution

There are four different points on a plane, P(xp,yp), Q(xq, yq), R(xr, yr) and S(xs, ys).
Write a Java program to test whether AB and CD are orthogonal or not.

Input:
xp,yp, xq, yq, xr, yr, xs and ys are -100 to 100 respectively and each value can be up to 5 digits after the decimal point It is given as a real number including the number of.
Output: Yes or No.

Sample Solution:

Java Code:

`````` import java.util.*;
import static java.lang.Math.*;

class Main{
public static void main(String args[]){
System.out.println("Input xp, yp, xq, yq, xr, yr, xs, ys:");
Scanner scan = new Scanner(System.in);
double x[] = new double[4];
double y[] = new double[4];
for(int i=0;i<4;i++){
x[i] = scan.nextDouble();
y[i] = scan.nextDouble();
}
double a = (x[0] - x[1]) * (x[2] - x[3]);
double b = (y[0] - y[1]) * (y[2] - y[3]);
if((float)a + (float)b == 0)
System.out.println("Two lines are orthogonal.");
else
System.out.println("Two lines are not orthogonal.");
}
}
```
```

Sample Output:

```Input xp, yp, xq, yq, xr, yr, xs, ys:
3.5 4.5 2.5 -1.5 3.5 1.0 0.0 4.5
Two lines are not orthogonal.
```

Pictorial Presentation:

Flowchart:

Java Code Editor:

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## Java: Tips of the Day

Check if at least two out of three booleans are true:

Rather than writing:

```if (someExpression) {
return true;
} else {
return false;
}
```

Write:

```return someExpression;
```

As for the expression itself, something like this:

```boolean atLeastTwo(boolean a, boolean b, boolean c) {
return a ? (b || c) : (b && c);
}
```

or this (whichever you find easier to grasp):

```boolean atLeastTwo(boolean a, boolean b, boolean c) {
return a && (b || c) || (b && c);
}
```

Ref: https://bit.ly/2OYPQD7