Răspuns :
P(dreptunghi)=2*(L+l)=180 ;
l=4/5 * L
=> 2*(L+4L/5)=180cm;
deci:
9L/5=180:2=90
L=90*5:9=50cm ;
l=4*50/5=40cm ;
l=4/5 * L
=> 2*(L+4L/5)=180cm;
deci:
9L/5=180:2=90
L=90*5:9=50cm ;
l=4*50/5=40cm ;