Two half-wave dipole antennas, each with impedance

Two half-wave dipole antennas, each with impedance of 75, are connected in parallel through a pair of transmission lines, and the combination is connected to a feed transmission line, as shown in Fig. 2.39 (P2.23 (a)).
All lines are 50 ??and lossless.
(a) Calculate Zin1, the input impedance of the antenna-terminated line, at the parallel juncture.
(b) Combine Zin1 and Zin2 in parallel to obtain ZL , the effective load impedance of the feed line.
(c) Calculate Zin of the feed line.