What Is a Reflex Angle?
A reflex angle is an angle that measures more than 180 degrees but less than 360 degrees. It represents the 'larger' portion of a full circle when two rays meet at a vertex, encompassing more than a straight line.
Section 2: Identifying a Reflex Angle
You can identify a reflex angle by its wide opening. For any common angle (acute, right, or obtuse) formed by two lines, the reflex angle is the corresponding larger angle on the outside that completes a full circle. Together, the interior angle and the reflex angle always sum to 360 degrees.
Section 3: A Practical Example
Imagine the hands of a clock at 7:00. The smaller angle between the hour and minute hand is an obtuse angle of 150 degrees. The larger angle, measured the long way around from the minute hand to the hour hand, is a reflex angle. This reflex angle would measure 360° - 150° = 210°.
Section 4: Importance in Geometry
Understanding reflex angles is crucial for describing complete rotations and spatial relationships in geometry and trigonometry. They are used in fields like computer graphics for object rotation, in robotics to define the full range of motion for a joint, and in navigation to describe bearings.