Find the value of x in the figure

How do i work this problem out using the equation a=pe^rt

Does anyone know how to do geometryme with this problem

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?