An obtuse triangle is a type of triangle that has one angle measuring more than 90 degrees. This means that the largest angle in the triangle is obtuse, while the other two angles are acute, each measuring less than 90 degrees. The sum of all angles in any triangle, including obtuse triangles, is always 180 degrees. In an obtuse triangle, the side opposite the obtuse angle is the longest side. These triangles can be classified further based on the lengths of their sides, such as isosceles or scalene. Understanding obtuse triangles is important in geometry and various applications, including architecture and engineering.