The presenter of the slide show perpendicular lines, which is located in the media section of chapter 3, states that the slope of the line l, that is perpendicular to the original line is (points : 1)

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?