Reflector 72 comprises a parabolic arc of which {HEAD ~ the focus} is at 76 and the directrix is at 77, the axis 79 of {TAIL ~ the parabola} being horizontal 
Reflector 72 comprises a parabolic arc of which { HEAD ~ the focus } is at 76 and the directrix is at 77 , the axis 79 of { TAIL ~ the parabola } being horizontal
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH