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# Standard Position of an Angle

An angle in the coordinate plane is in standard position if its vertex is at the origin and one ray is on the positive axis. The ray on the axis is called the initial side. The other ray is the terminal side of the angle.
The measure of an angle can be positive or negative.
• If the terminal side is rotated counterclockwise, then the measure of the angle is positive.
• If the terminal side is rotated clockwise, then the measure of the angle is negative.
Move the slider to see how the angle measure changes.