Reflex angle facts for kids

The reflex angle is a special type of angle. It's bigger than a straight angle (which is 180°) but smaller than a full circle (which is 360°). Think of it as the "outside" part of an angle!

What is an Angle?

An angle is formed when two lines or "rays" meet at a point called a "vertex." Imagine opening a pair of scissors; the blades form an angle. Angles are measured in degrees (°).

Different Types of Angles

There are several types of angles, and each has a specific size:

• Acute angle: This angle is small, less than 90°. Think of the sharp corner of a slice of pizza.
• Right angle: This angle is exactly 90°. It looks like the corner of a square or a book.
• Obtuse angle: This angle is wider than a right angle but smaller than a straight line. It's more than 90° but less than 180°.
• Straight angle: This angle forms a straight line and measures exactly 180°.
• Reflex angle: This is the angle we're talking about! It's larger than 180° but less than 360°.
• Full rotation (or full angle): This is a complete circle, measuring exactly 360°.

How to Understand a Reflex Angle

Imagine you have two clock hands. If they point in opposite directions, they form a straight angle (180°). Now, if you keep moving one hand past the straight line, the larger angle that forms is a reflex angle. It's the "long way around" between the two lines.

Measuring a Reflex Angle

You can measure a reflex angle using a protractor. However, it's often easier to measure the smaller angle (the non-reflex angle) formed by the two lines and then subtract that from 360°.

For example:

• If the smaller angle is 60°, the reflex angle would be 360° - 60° = 300°.
• If the smaller angle is 120°, the reflex angle would be 360° - 120° = 240°.

Where Can You See Reflex Angles?

Reflex angles appear in many places around us:

• Clock hands: When the time is, for example, 4:00, the smaller angle between the hands is 120°. The larger angle (the reflex angle) is 240°.
• Shapes: Sometimes, the interior angles of complex shapes can be reflex angles.
• Doors: If you open a door very wide, past a straight line, the angle formed by the door and the wall on the outside could be a reflex angle.

Reflex angles are important in geometry and help us describe the position and rotation of objects more completely.

Images for kids

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  An angle formed by two rays emanating from a vertex.