Question

Un dreptunghi are perimetru de 78 cm iar latimea cu 5 pe 8 aria ete egala cu???????
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Answer 1

P=78 cm

P=(L+l)·2

l=5/8 =>(L+5/8)·2=78 => L+5/8=39 => L = 39-5/8 = $39 -\frac{5}{8} = \frac{312-5}{8}=\frac{307}{8}$ cm

A = l·L = $\frac{5}{8} . \frac{307}{8} = \frac{1535}{64}$  cm²