-1 9 setxrange
-1 7 setyrange

/A {1 0} def
/B {3 4} def
/C {5 2} def
/D {7 4.5} def
/E {8 6} def

traceaxes
axesarrow
ticks

[1 2 4 4.5 6] {ymark} apply
[1 3 5 7 8] {xmark} apply
[B C D E] dashpoints
1.7 setlinewidth

[A {80 dir} .. B {right} .. C {right} .. D .. E ] draw