1. The problem is to classify a triangle by its sides based on the given description. 2. Triangles are classified by their sides as follows: - Equilateral: all three sides are equal. - Isosceles (but not equilateral): exactly two sides are equal. - Scalene: all three sides are different. 3. The triangle described has a right angle and an obtuse angle, which is not possible because the sum of angles in a triangle is 180 degrees and a right angle is 90 degrees, so the other two angles must sum to 90 degrees, meaning none can be obtuse. 4. Since the triangle is described as right-angled and having an obtuse angle, this is contradictory, but focusing on side classification: 5. A right triangle can be scalene or isosceles but not equilateral (since equilateral triangles have all angles 60 degrees). 6. Without side lengths, we cannot definitively classify the triangle by sides, but given the right angle and the description, it is likely scalene or isosceles. 7. Therefore, the triangle is most likely scalene or isosceles but not equilateral.