Maths glossary · Australia
Obtuse angle
An angle that measures more than 90 degrees and less than 180 degrees.
An obtuse angle is wider than a right angle but not a straight line.
Example: A 120 degree angle is obtuse. A clock's hands make an obtuse angle at 4 o'clock.
Lessons, worksheets, practice and tools on this: Geometry and shapes.
Related words
- Angle: The amount of turn between two lines that meet at a point.
- Symmetry: When one half of a shape is a mirror image of the other half.
- Parallel lines: Lines in the same flat surface that stay the same distance apart and never meet.
- Perpendicular lines: Two lines that meet to form a right angle.
- Polygon: A closed flat shape made of straight sides.
- Quadrilateral: A polygon with exactly 4 sides.
- Right angle: An angle that measures exactly 90 degrees, like the corner of a square.
- Acute angle: An angle that measures less than 90 degrees.
- Vertex: A point where two or more lines or edges meet. The plural is vertices.
- Diameter: The distance across a circle through its center.
- Radius: The distance from the center of a circle to its edge.
- Circumference: The distance around a circle.
- Prism: A solid shape with two identical, parallel bases and flat sides that are rectangles.
- Pyramid: A solid shape with a flat base and triangle faces that meet at one point.