Where does the arrow plotting end?

[psads-git]

The following code produces the figure below. Could you please explain why we apparently need to use different side paddings (left: 2.8em, right: 1em) to get the formula equally distant from both arrows? I suspect the arrow head is not the end coordinate when cetz plots the first arrow. Thanks!

#import "@preview/cetz:0.2.2"

#cetz.canvas({
  import cetz.draw: *

  line((0, 0), (2, 0), mark: (end: ">", fill: black), name: "line")
  content((rel: (1, 0)), align(center, $a^2 = b^2+c^2$), 
      padding: (left: 2.8em, right: 1em), name: "form")
  line("form.east", (rel: (2, 0)), mark: (end: ">", fill: black))
})

[fenjalien]

The arrow is drawn at the end coordinate, its behaving like that because you're using relative coordinates to place the equation. You should use anchors to place it intead:

#import "@preview/cetz:0.2.2"

#cetz.canvas({
  import cetz.draw: *

  line((0, 0), (2, 0), mark: (end: ">", fill: black), name: "line")
  content(
    "line.end",
    align(center, $a^2 = b^2+c^2$), 
    padding: (left: 1em, right: 1em),
    name: "form",
    anchor: "west"
  )
  line("form.east", (rel: (2, 0)), mark: (end: ">", fill: black))
})

[psads-git]

Thanks, @fenjalien, that works perfectly!