Which of the following triangles has all sides and angles equal?

The correct answer is that an equilateral triangle has all sides and angles equal. In an equilateral triangle, each of the three sides is of equal length, which directly leads to each of the three angles being equal as well. This means that every interior angle measures 60 degrees, as the sum of angles in any triangle is always 180 degrees. The defining characteristic of equilateral triangles is this uniformity in both side lengths and angle measurements, making them a fundamental shape in geometry.

In contrast, a scalene triangle is defined by having all sides of different lengths and, consequently, all angles are also different. An isosceles triangle has at least two sides that are equal in length, leading to at least two angles being equal, but it does not meet the criteria of having all sides and all angles equal. Lastly, a right triangle is specifically defined by having one angle that measures exactly 90 degrees. While it can have two equal sides (making it an isosceles right triangle), it does not have all sides and angles equal.

Thus, the clear distinction of an equilateral triangle is its uniformity across all dimensions, making it the only classification among the options provided that meets the criterion of all sides and angles being