Answer: (a) 10 kmSolution:
Here,$$ RO = OS = 4 \ km $$ Similarly,$$ PR = QS = 3 \ km $$ And,$$ PO = OQ $$ Now,$$ PO = \sqrt{(PR)^2 + (RO)^2} $$ $$ = \sqrt{3^2 + 4^2} $$ $$ = \sqrt{9 + 16} $$ $$ = \sqrt{25} = 5 $$ So,$$ PO = OQ = 5 \ km $$ Hence, the shortest distance between P and Q,$$ PQ = PO + OQ $$ $$ = 5 + 5 $$ $$ = 10 \ km $$