UPSC Civil Services 2016 Prelims General Studies Paper II

A person climbs a hill in a straight path from point 'O' on the ground in the direction of north-east and reaches a point 'A' after travelling a distance of 5 km. Then, from the point 'A' he moves to point 'B' in the direction of north-west. Let the distance AB be 12 km . Now, how far is the person away from the starting point 'O'