Obtuse angle facts for kids
An obtuse angle is a type of angle that is bigger than 90 degrees (90°) but smaller than 180 degrees (180°). Think of it as being wider than a perfect corner, but not completely flat.
It's larger than an acute angle, which is a small, sharp angle less than 90°. It's also smaller than a straight angle, which measures exactly 180° and looks like a straight line.
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Measuring Obtuse Angles
You can measure angles using a tool called a protractor. A protractor is usually a half-circle shape with numbers marked on it. To measure an obtuse angle:
- Place the center of the protractor on the angle's corner (called the vertex).
- Line up one side of the angle with the 0° mark on the protractor.
- Read the number where the other side of the angle crosses the protractor's scale.
- If the angle is between 90° and 180°, it's an obtuse angle!
Obtuse Angles in Shapes
Obtuse angles are very common in many different shapes and objects around us.
- For example, a regular pentagon (a five-sided shape) has interior angles that are all obtuse.
- A regular hexagon (a six-sided shape) also has interior angles that are obtuse.
- You can often find obtuse angles in the hands of a clock, especially when the time is, for instance, 4:00 or 8:00.
- Many roofs on houses have obtuse angles where the different sections meet.
Related Angles
Understanding obtuse angles is easier when you know about other types of angles too.
Acute Angle
An acute angle is an angle that measures less than 90°. It looks sharp, like the tip of a knife.
Right Angle
A right angle measures exactly 90°. It forms a perfect square corner, like the corner of a book or a wall.
Straight Angle
A straight angle measures exactly 180°. It looks like a straight line.
Reflex Angle
A reflex angle is an angle that measures more than 180° but less than 360°. It's like looking at the "outside" of an angle.
Images for kids
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An angle formed by two rays coming from a single point.
