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rombul abcd are <b=120 °si bd=4cm. Pabcd=?, Aabcd=?​

Răspuns :

rombul ABCD are <B=120 °si BD=4cm.

P ABCD=?,

A ABCD=?

rezolvare

<A=180⁰-120⁰=60⁰ => ∆ ABD echilateral

=>AB= BD=4cm

P ABCD=4×AB=4×4=16cm

aria AB ×h /2

h∆echilateral= AB √3/2

aria ABCD= AB ²√3/2= 4²√3/2=8√3cm²

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