PLEASE HELP ME WITH THIS PROBLEMm

Me, prove a quadrilateral with vertices g(1,-1), h(5,1), i(4,3) and j(0,1) is a rectangle using the parallelogram method and a rectangle method.

Two cyclists 84 miles apart start riding toward each other at the same. one cycles 2 times as fast as the other. if they meet 4 hours later, what is the speed (in mi/h) of the faster cyclist?

Describe the symmetry of the figure. identify lines of symmetry, if any. find the angle and the order of any rotational symmetry.