Sure, I can help you with that. The angle of depression is an angle formed between the horizontal line and the line of sight when an observer looks downwards at an object. It is used to measure the distance of the object from the ground or the observer.
In this problem, we can draw a right triangle ABC where A is the teacher, B is the pupil and C is the point on the ground below the teacher. The height of the stage is 1.5 m, so AC = 1.5 m + 1.5 m = 3 m. The angle of depression of the pupil from the teacher is 25°, so ∠BAC = 25°. We need to find BC, which is the distance between the teacher and the pupil.
Using trigonometry, we can write:
tan(25°) = AC/BC
BC = AC/tan(25°)
BC = 3/tan(25°)
BC ≈ 6.4 m
Therefore, the distance between the teacher and the pupil is about 6.4 m.