Quadrilateral PQRS has vertices P(- 3, - 4), Q(9, 5), R(- 1, 10) , and S(- 5, 7) . Prove that quadrilateral PQRS is an isosceles trapezoid. (show work pls)

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?