A straight line from A to E runs along both edges.
Straight, bent or tilted?
Bourdon illusion
Do the edges from A to C to E make a straight line?
Yes, though it looks bent at C.
Why? Your brain judges each edge against the other edge of its own wedge, and misjudges the angle between them.
Picture: Mabit1, CC BY-SA 4.0 · Wikipedia(opens in a new tab)