I got all my pre-calc questions answered! THANK YOU to everyone, because I know there are amazing people on here, not just 5 year olds! Great work we've put in here, answering each others questions!

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?