[" 16.A common tangent to "9x^(2)-16y^(2)=144" and "x^(2)+y^(2)=],[[" (a) "y=(3)/(sqrt(7))x+(15)/(sqrt(7))," (b) "y=3sqrt((2)/(7))x+(15)/(sqrt(7))],[" (c) "y=2sqrt((3)/(7))x+15sqrt(7)," (d) none of these "]]