Let us visualise the given situation as shown in the image. Let ‘I’ be the initial position of the body, it moves 10 km to reach N and from there 20 km towards the east to point E.
We need to find the displacement of the body from point I to point E which is a diagonal of a right triangle INE.
We know that we can use the Pythagorean Theorem to find the length of the diagonal of a right triangle.