Question

Daca marim cu 11 cm latimea unui dreptunghi,btinem un patrat cu perimetrul de 112 cm.Care este perimetrul dreptunghiului?

Answer 1

$2L+2(l+11)= P_\square\\\\ 2L+(2l+22)=4l \\\\ \boxed{L=l+11} \\\\ 2L+2L=112 \\\\ 4L=112 \ \ |:4 \\\\ \boxed{\boxed{L=28}} \\\\ L=l+11 \\\\ 28=l+11 \\\\ l=28-11 \\\\ \boxed{\boxed{l=17}} \\\\ P_\rectangle=2L+2l= \\\\ =2*28+2*17= \\\\ =56+34= \\\\ =\boxed{90}$