Answer:
B, C, D
Step-by-step explanation:
1. A is not possible because right and obtuse both define triangle angles. An angle cannot be obtuse and right at the same time.
2. B is possible because a right triangle can have all sides of different length.
3. C is possible because a scalene triangle can have an obtuse angle.
4. D is possible because an isosceles triangle can have all acute angles.
5. E is not possible because of how equilateral triangles work. When a triangle is equilateral, it is also equiangular, meaning all of its angles are the same. The angles on every type of triangle always add up to 180 degrees. If a triangle is equiangular, the 180 degrees are divided evenly, with every angle being 60 degrees, which is acute. Therefore, an equilateral triangle cannot have a right angle.
6. F is not possible because isosceles and scalene both refer to the side lengths of triangles. A triangle cannot be isosceles and scalene at the same time.
7. G is not possible because equilateral triangles cannot have angles other than 60 degrees and therefore cannot be obtuse.
