Definition:Triangle (Geometry)/Acute

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Definition

An acute triangle is a triangle in which all three of the vertices are acute angles.


Also known as

An acute triangle is also known as an acute-angled triangle.


Euclid's Definition

In the words of Euclid:

Further, of trilateral figures, a right-angled triangle is that which has a right angle, an obtuse-angled triangle that which has an obtuse angle, and an acute-angled triangle that which has its three angles acute.

(The Elements: Book $\text{I}$: Definition $21$)


Sources