If H $=4$afi $-3$a$0+5$az$,$ at $(1,$ x$/2,0)$ the component of H parallel to surface p $=1$ is $($a$)4$ap $($b$)5$az $($c$)-3$a$*($d$)-3$a$,,,+5$a$2($e$)5$arf, $+3$az