What type of triangle can also be an acute triangle?

An acute triangle is defined as a triangle in which all three interior angles are less than 90 degrees. Among the options presented, an isosceles triangle can be classified as an acute triangle when the angles at the base of the isosceles triangle are each less than 90 degrees, and the vertex angle is also less than 90 degrees.

It is important to note that an isosceles triangle is characterized by having at least two sides that are equal in length, which allows for a variety of angle measures. If the two equal angles are each acute, the overall configuration forms an acute triangle. Additionally, isosceles triangles can also be right (having one 90-degree angle) or obtuse (having one angle greater than 90 degrees).

In contrast, while an equilateral triangle (which has all sides and angles equal, each measuring exactly 60 degrees) is always acute, the correct answer in this context is isosceles because it accommodates acute angles but can also fit other classifications. Thus, the flexibility of an isosceles triangle regarding angle measurement allows it to be classified in multiple categories, one of which is acute.