(a) Let r1 be the length of the direct path in Figure 9.4. Let r2 be the length of the reflected path (summing the path length from the transmitter to ground plane and the path length from ground plane to receiver). Show that as r increases, r2 -r1 is asymptotically equal to b/r for some constant r; find the value of b.
(c) Explain why this asymptotic expression remains valid without first approximating the denominator r2 in (9.88) by r1