Acute Angles (Mathematics Glossary)
What Is an Acute Angle?
An acute angle is an angle of less than 90°.
An angle less than a right angle is an acute angle.
The Oxford English Dictionary defines an acute angle as "a plane angle: less than 90 degrees."
Real Examples of Acute Angles
The angles below are all acute angles:
What's in a Name?
Acute comes from the Latin word 'acutus' meaning "sharp".
An acute angle makes a sharp point.
Euclid and Acute Angles
Euclid defines angles in his book, Elements.
Definition 12: "An acute angle is an angle less than a right angle".
Acute triangles are triangles that have all acute angles.