Video narration
What kind of name should a triangle in your notebook have? They all have three sides, but they are not all classified the same way. First, compare side lengths. Three equal sides make an equilateral triangle. Two equal sides make an isosceles triangle. Three different sides make a scalene triangle. Matching marks in your notebook show which sides are equal. Now switch your test. The same triangle can be judged by its angles instead of its sides. If every angle is less than 90 degrees, it is acute. If one angle equals 90 degrees, it is right-angled. If one angle is greater than 90 degrees, it is obtuse. Check the angle marking, not just the shape. So, what name does your triangle have? In your notebook, inspect its sides and its angles: triangles get different names by their sides or by their angles.