Language: Java

import java.util.*;
import java.math.*;

public class Main{
	private static final Scanner scan = new Scanner(System.in);

	public static void main(String[] args){
		List<String> list = new ArrayList<String>();

		int n = scan.nextInt();
		for(int i = 0; i < n; i++){
			BigDecimal x1 = scan.nextBigDecimal();
			BigDecimal y1 = scan.nextBigDecimal();
			BigDecimal x2 = scan.nextBigDecimal();
			BigDecimal y2 = scan.nextBigDecimal();
			BigDecimal x3 = scan.nextBigDecimal();
			BigDecimal y3 = scan.nextBigDecimal();
			BigDecimal x4 = scan.nextBigDecimal();
			BigDecimal y4 = scan.nextBigDecimal();

			BigDecimal ax = x2.subtract(x1);
			BigDecimal ay = y2.subtract(y1);

			BigDecimal bx = x4.subtract(x3);
			BigDecimal by = y4.subtract(y3);

			BigDecimal thetaA = Math.abs(ax) * Math.tan(Math.abs(ay)
								 / Math.abs(ax));
			BigDecimal thetaB = Math.abs(bx) * Math.tan(Math.abs(by)
								 / Math.abs(bx));
			
			if(thetaA == thetaB){
				list.add("YES");
			} else{
				list.add("NO");
			}
		}

		for(String s : list){
			System.out.printf("%s\n", s);
		}
	}
}

Compiler output:
Main.java:27: error: no suitable method found for abs(BigDecimal)
			BigDecimal thetaA = Math.abs(ax) * Math.tan(Math.abs(ay)
			                        ^
    method Math.abs(int) is not applicable
      (argument mismatch; BigDecimal cannot be converted to int)
    method Math.abs(long) is not applicable
      (argument mismatch; BigDecimal cannot be converted to long)
    method Math.abs(float) is not applicable
      (argument mismatch; BigDecimal cannot be converted to float)
    method Math.abs(double) is not applicable
      (argument mismatch; BigDecimal cannot be converted to double)
Main.java:27: error: no suitable method found for abs(BigDecimal)
			BigDecimal thetaA = Math.abs(ax) * Math.tan(Math.abs(ay)
			                                                ^
    method Math.abs(int) is not applicable
      (argument mismatch; BigDecimal cannot be converted to int)
    method Math.abs(long) is not applicable
      (argument mismatch; BigDecimal cannot be converted to long)
    method Math.abs(float) is not applicable
      (argument mismatch; BigDecimal cannot be converted to float)
    method Math.abs(double) is not applicable
      (argument mismatch; BigDecimal cannot be converted to double)
Main.java:28: error: no suitable method found for abs(BigDecimal)
								 / Math.abs(ax));
								       ^
    method Math.abs(int) is not applicable
      (argument mismatch; BigDecimal cannot be converted to int)
    method Math.abs(long) is not applicable
      (argument mismatch; BigDecimal cannot be converted to long)
    method Math.abs(float) is not applicable
      (argument mismatch; BigDecimal cannot be converted to float)
    method Math.abs(double) is not applicable
      (argument mismatch; BigDecimal cannot be converted to double)
Main.java:29: error: no suitable method found for abs(BigDecimal)
			BigDecimal thetaB = Math.abs(bx) * Math.tan(Math.abs(by)
			                        ^
    method Math.abs(int) is not applicable
      (argument mismatch; BigDecimal cannot be converted to int)
    method Math.abs(long) is not applicable
      (argument mismatch; BigDecimal cannot be converted to long)
    method Math.abs(float) is not applicable
      (argument mismatch; BigDecimal cannot be converted to float)
    method Math.abs(double) is not applicable
      (argument mismatch; BigDecimal cannot be converted to double)
Main.java:29: error: no suitable method found for abs(BigDecimal)
			BigDecimal thetaB = Math.abs(bx) * Math.tan(Math.abs(by)
			                                                ^
    method Math.abs(int) is not applicable
      (argument mismatch; BigDecimal cannot be converted to int)
    method Math.abs(long) is not applicable
      (argument mismatch; BigDecimal cannot be converted to long)
    method Math.abs(float) is not applicable
      (argument mismatch; BigDecimal cannot be converted to float)
    method Math.abs(double) is not applicable
      (argument mismatch; BigDecimal cannot be converted to double)
Main.java:30: error: no suitable method found for abs(BigDecimal)
								 / Math.abs(bx));
								       ^
    method Math.abs(int) is not applicable
      (argument mismatch; BigDecimal cannot be converted to int)
    method Math.abs(long) is not applicable
      (argument mismatch; BigDecimal cannot be converted to long)
    method Math.abs(float) is not applicable
      (argument mismatch; BigDecimal cannot be converted to float)
    method Math.abs(double) is not applicable
      (argument mismatch; BigDecimal cannot be converted to double)
6 errors