Question

Uitativa la exercitiile din poza. dau coronita la cel mai bun raspuns. Multumesc !

Answer 1

1.3x+13=31
3x=31-13
3x=18
x=18:3
x=6
2.$\frac{l}{L} = \frac{4}{5}$
$\frac{l}{20}= \frac{4}{5}$
$l=4*4=16cm$
$P=(l+L)*2=(16+20)*2=36*2=72cm$
3.$13 ^{2} =5 ^{2} +12$
$169=125+44$
$169=169=\ \textgreater \ tringhiul ABC este dreptunghic$
4.$A_{ABCD} = \frac{AC*BD}{2} = \frac{14*20}{2} =140$