P=430cm; b=1/2 B, P= AB+CD+DC+AD =430 ; AD II BC; AB=b+15; CD=b+15:
P=(b+15)+(2b)+(b+15)+b=430; b+15+2b+b+15+b=430; 5b=430-30=400:5;b=80'
b=8o cm,B=2 x 80 =160 cm; A=80+15=95; CD=430-(80+160+95) =430-335=95 cm
rezulta ca ABCD trapez isoscel( AB=CD)