Definition:Re-entrant Angle

Theorem

Let $P$ be a polygon.

Let $V$ be a vertex of $P$ whose internal angle $A$ is greater than $180 \degrees$.

Then $A$ is known as a re-entrant angle.

Also see

• Definition:Salient Angle

• Results about re-entrant angles can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): concave polygon
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): interior angle: 1.
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): re-entrant angle
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): concave polygon
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): interior angle: 1.
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): re-entrant angle