The boy walked 40 m from the house towards the east. Then he turned north and walked 30 m. At what distance

The boy walked 40 m from the house towards the east. Then he turned north and walked 30 m. At what distance (in meters) from the house was the boy?

Let’s denote the house by point A, then the point at which the boy turned north we will denote by point C, and the point at which the boy found himself after walking 30 m to the north will be designated by point B.
Thus, we got a rectangular △ ABC with a straight line ∠C. Therefore, AC = 40 m and BC = 30 m are the legs of this triangle, and AB is the hypotenuse, since it lies opposite the right angle.
By the Pythagorean theorem, we find the length of the hypotenuse AB:
AB = √ (AC² + BC²) = √ (40² + 30²) = √ (1600 + 900) = √2500 = 50 (m).
Answer: the boy was at a distance of 50 meters from the house.