Question

La problema 1 de la subiectul 3 am nevoie de ajutor la subpunctele b) si c)

Answer 1

b)Avem,BC=60(ip,AD=60cm)
Mai,avem,BM=60cm(ip.)
=>ΔCBM,echilat.=>m(∡CBM)=60°
ABllCD
ADllBC(def.paralelogr.)

=>∡DAB≡∡CBM(paralele,taiate,de,secanta)=>m(∡DAB)=60°

c)AB=BE=80(ip.)
BM=60(ip.)=>ME=20(baza,mica,a,trapezului)
BE=CF(def.paralelogr.)(baza,mare,a,trapezului)
Ducem,EE',inaltime(E'∈CF)
E'F=30(cateta,opusa,∡E'EF=30°)
EF=60(ip.)
=>(t.Pit)EE'²=3600-900=2500
EE'=50

Aria=(80+20)50/2=100x25

=>Aria=2500cm²<2600cm²