Definition:Directed Angle

Definition

Let $\LL_1$ and $\LL_2$ be two lines which intersect at a point $\PP$.

The directed angle from $\LL_1$ to $\LL_2$ is defined as the amount of rotation about $\PP$ required to bring $\LL_1$ into correspondence with $\LL_2$.

If the rotation about $\PP$ is anticlockwise, then the directed angle is positive in sign.

If the rotation about $\PP$ is clockwise, then the directed angle is negative in sign.

Also see

• Results about directed angles can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): angle
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): directed angle
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): angle
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): directed angle