A man starts from his home. He walks 20 metres to the west, then turns right and walks 30 metres, and thereafter walks 10 metres to the east. Find the aerial distance between the end point and the starting point.

The aerial distance is 10 root 10 m.

Take start at (0, 0); walking 20 m west gives (-20, 0).

A right turn faces north; 30 m north gives (-20, 30).

Then 10 m east gives (-10, 30).

Distance = root(10^2 + 30^2) = root(100 + 900) = root 1000.

root 1000 = 10 root 10 m.