Ducem BE⊥DC deci triung BEC este dreptunghic si isoscel (masura lui C este 45 grade) deci BE=EC
Aplic teorema Pitagora in BEC
BC²=BE²+EC²=EC²+EC²=2EC²
16²=2EC² deci EC²=256/2=128 deci EC=√128=8√2=BE
ABED dreptunghi deci BE=AD=8√2
DC=DE+EC=3√2+8√2=11√2
perimetrul trapez=AB+AD+DC+BC=3√2+8√2+11√2+16=22√2+16=2(8+11√2) cm