Răspuns:
[tex]trapez[/tex]
[tex]B=3a+c[/tex]
[tex]b=2c+3b[/tex]
[tex]a+b+c=12[/tex]
[tex]h=12[/tex]
[tex]A=?[/tex]
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[tex]A=\frac{(B+b)*h}{2} =\frac{(3a+c+2c+3b)*12}{2} =\frac{(3a+3c+3b)*12}{2} =\frac{3*(a+c+b)*12}{2} =\frac{3*12*12}{2} =216[/tex]
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