Răspuns:
Ppatrat=4l
l=28cm
P=4·28=112 cm perimetrul patratului
P patrat=Pdreptunghi
-----------------------------
Pdreptunghi=2(L+l)=112 cm
a)L=l+6
112=2(l+6+l)
112=2(2l+6)
112=4l+12=>4l=112-12=>4l=100=>l=100:4=>l=25 cm
L=25+6=31 cm
L=31 cm,l=25cm
-----------------------
b) l=L/3
112=2(L/3+L)
112:2=L/3+L
56=L/3+L aducem la acelasi numitor
168=L+3L
L=168:4=>L=42 cm
l=42:3=>l=14 cm
L=42cm,l=14cm