How Can You Identify Obtuse and Acute Angles Easily?
FAQs on What's the Difference Between an Obtuse and an Acute Angle?
1. What is the difference between an acute and an obtuse angle?
An acute angle measures less than 90 degrees, while an obtuse angle is greater than 90 degrees but less than 180 degrees.
Key differences:
- Acute angle: Less than 90°
- Obtuse angle: More than 90° and less than 180°
- Acute angles appear sharper, while obtuse angles look wider
- Both are types of angles studied in geometry
2. What is an acute angle?
An acute angle is an angle that measures less than 90 degrees.
Features:
- Always less than 90°
- Smaller than a right angle
- Common examples: 30°, 45°, and 60°
- Often found in triangles and polygons
3. What is an obtuse angle?
An obtuse angle is an angle that measures more than 90 degrees but less than 180 degrees.
Key points:
- Greater than 90°, smaller than 180°
- Wider than a right angle
- Common examples: 120°, 135°, 150°
4. How do you identify an acute and an obtuse angle visually?
To identify the type of angle:
- Acute angles look sharp and are smaller than a right angle (less than 90°)
- Obtuse angles look wider and open more than a right angle (more than 90°, but less than 180°)
5. Can a triangle have both acute and obtuse angles?
No, a triangle cannot have both acute and obtuse angles together.
Reason:
- A triangle can have only one obtuse angle at most
- The other two angles must be acute for the sum to be 180°
- If a triangle has all angles less than 90°, it is called an acute triangle
6. What examples in daily life use acute and obtuse angles?
Examples of acute angles in real life include:
- The tip of a slice of pizza
- Scissors' pointed end
- A house roof peak
Examples of obtuse angles include:
- The angle when a book is opened wide
- The hands of a clock at 10:15
- A ramp gently sloping upwards
7. How do you measure an acute and an obtuse angle?
To measure any angle, use a protractor.
Steps:
- Place the midpoint of the protractor at the angle's vertex
- Align one side of the angle with the zero line
- Read the measurement on the scale where the other side meets
An acute angle will show less than 90°, while an obtuse angle will show between 90° and 180°.
8. Can an angle be both acute and obtuse?
No, a single angle cannot be both acute and obtuse at the same time.
- Acute angles are always below 90°
- Obtuse angles are always between 90° and 180°
9. Which triangles have obtuse angles?
A triangle with one obtuse angle is called an obtuse triangle.
- Only one angle can be obtuse (more than 90°)
- The other two angles will always be acute
- Sum of all angles in any triangle: 180°
10. What is the sum of angles in a triangle and how do acute and obtuse angles fit in?
The sum of all three angles in a triangle is always 180 degrees.
- A triangle may have all acute angles (acute triangle)
- Or one obtuse angle and two acute angles (obtuse triangle)
- It cannot have more than one obtuse angle
11. List the main types of angles with their degree ranges.
The main types of angles and their degree measures are:
- Acute angle: less than 90°
- Right angle: exactly 90°
- Obtuse angle: more than 90°, less than 180°
- Straight angle: exactly 180°
- Reflex angle: more than 180°, less than 360°






















