Based on the Triangle Inequality Theorem, the possible type of triangles from the options provided include:
- Obtuse Equilateral: Impossible because an equilateral triangle has all angles equal to 60 degrees, which cannot be obtuse.
- Right Isosceles: Possible, as a right triangle can have two equal sides, making it isosceles.
- Equilateral Scalene: Impossible, as an equilateral triangle cannot have sides of different lengths (which is the definition of scalene).
- Right Equilateral: Impossible, as an equilateral triangle has all angles equal to 60 degrees, and thus cannot be right-angled.
Based on this analysis, the only possible type of triangle from your options is the right isosceles triangle.