Question

Drept ABCD are aria egala cu 21 cm pătrați si AD=3cm .Calculati Pabcd​

Answer 1

$\it \mathcal{A} =L\cdot\ell \Rightarrow 21=L\cdot3|_{:3}\Rightarrow L=7\ cm\\ \\ \mathcal{P}=2\cdot(L+\ell)=2\cdot(7+3)=2\cdot10=20\ cm$