Little Johnny Red is standing on the edge of a lake, and the place where he stands is $1$ yard above the water level. Johnny's toy boat is floating in the lake, and the boy is pulling it ashore with a string (that is more than $2$ yards long). When Johnny pulls in $1$ yard of string, will the boat advance towards the shore by (i) more than one yard, (ii) exactly one yard, or (iii) less than one yard?
(Note: This puzzle is tagged as [math]. The solution does neither require lateral thinking nor physics.)