In math, the word 'acute' refers to an angle less than 90°, or to a shape involving angles less than 90°.
It is the opposite of
obtuse, which refers to an angle greater than 90°.
Any angle with a measure less than 90°, for example:
For more on this see Acute angle definition.
2. Acute triangle
A triangle where all interior angles have a measure less than 90°, for example:
For more on this see Acute triangle definition.
(C) 2009 Copyright Math Open Reference. All rights reserved