Question

Subiectul || problema 2 RAPID!!!

Answer 1

Răspuns:

Explicație pas cu pas:

∡CBD=∡ABD  constructie

∡ABD=∡BDC     alt interne   ⇒∡CBD=∡BDC   ⇒ΔBDC  este isoscel

⇒BC=CD=30 cm

Construim CT⊥AB      ⇒in Δ dreptunghic CTB    BC=30 cm

TB=AB-CD=48-30=18 cm

T Pitagora

BC²=CT²+TB²         ⇒CT²=BC²-TB²=30²-18²=(30-18)(30+18)=12·48=12·12·4

CT=12·2 cm=24 cm=AD  inaltimea

Aabcd=(AB+CD)·AD/2=(48+30)·24/2=78·12 cm²=936 cm²

Aabd=AD·AB/2=24·48/2=24²=576 cm²

A bcd=A abcd-Aabd=936 cm²-576cm²=360 cm²  Raspuns: c