An obtuse-angled triangle can be

1. right-angled

2. isosceles

3. equilateral

4. none of these

An obtuse-angled triangle has one obtuse angle (greater than 90°).

• It cannot be right-angled (already has obtuse angle, sum would exceed 180°).

• It cannot be equilateral (equilateral has all 60° angles, all acute).

• It can be isosceles (e.g., 100°, 40°, 40° — two equal angles, two equal sides).

Hence, option 2 is the correct option.