Examining the front planar truss of this bridge, how many zero force members are observed? Number the members 1 through 21. If the right side of the truss is supported

by a rocker and the left side is supported by a hinge, list the members that can be inspected for tension or compression? If a 500 lb load was applied downward on the pin between the green star and the blue box,determine the force in the upper left horizontal member (orange arrow), and the two members directly below (purple pentagons).