Question

the coordinates of the endpoints of line AB and line CD are A(x1, y1), B(x2, y2), C(X3,Y3), and D(x4, y4). which condition proves that line AB is parallel the CD?

Answer 1

Find the slope for the two lines and state that they are equal (condition for parallel lines)

Slope of line AB

[y2 - y1] / [x2 - x1]

Slope of line CD

[y4 - y3] / [x4 - x3]

Condition

[y2 - y1] / [x2 - x1] = [y4 - y3] / [x4 - x3]