First, we have to calculate the slopes of each line:
Slope m = variation on y / variation on x
• Line a.
m = (6-4)/ (5-(-1))= 2/6 =1/3
• Line b:
m= (2-1) / 3-(-1) = 1/4
• Line C:
m = (0-(-2))/ (3-(-3)) = 2/6 = 1/3
• Line d:
m= (-2-6)/(3-1) = -8/2 = -4
Parallel lines have the same slope.
a= 1/3, c= 1/3
a and c are parallel lines
Perpendicular lines have inverse reciprocal slopes.
b= 1/4, d =-4
-4 is the inverse reciprocal of 1/4
b and d are perpendicular lines.