Compare and contrast the formulas for P(A and B) for dependent and independent events. What is the relationship between P(B) and P(B|A) and can one equation be used both independent and dependent events?

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?