====== Area ======
{{tag>geometry function}}
===== Description =====
Counting surface of rectangle

**Source**:  PROLOG str. 19 Wydawnictwo PLJ Warszawa 1991 ISBN 83-85190-63-5
===== Download =====
Program source code: {{area.pl}}
===== Listing =====
<code prolog>
dlugosc(blat, 10).
szerokosc(blat, 20).

powierzchnia(X, Y) :- dlugosc(X, D), szerokosc(X, S), Y is D*S.</code>
===== Comments =====