Topic 5: Parallel, Perpendicular, or neither?! For questions 19-21, determine if overline AB and vec CD are parallel, perpendicular or neither. 19. A(- 11, 5) B(- 8, 4) C(8,- 7) D(- 1, - 4) Slope of AB Slope of CD Types of Lines 20. A(- 3, 8) B(1, 15) C(10,- 9) D(3, - 5) Slope of AB Slope of overleftrightarrow CD Types of Lines 21. A(9, - 3) B(9, 4) C(- 2,10) D(- 2, 6) Slope of overleftrightarrow AB Slope of overleftrightarrow CD Types of Lines