Question

Un dreptunghi are latimea cat jumatatea lungimii si perimetrul de 126 cm.Aflati aria lui.

Answer 1

$l = L \div 2$

$P=126 \: cm$

$P=2(L+l)$

$2(L+L \div 2) = 126 \: | \div 2$

$L + L \div 2 = 63 \: | \times 2$

$2L +L = 126$

$3L = 126$

$L = 126 \div 3$

$L = 42 \: cm$

$l = L \div 2$

$l = 42 \div 2$

$l = 21 \: cm$

$A=L\:\times\:l=42\times21=882 \:{cm}^{2}$