Question

Dau 30 de puncte, ajutor îmi trebuie în 5 minute, dau și coroana!!

Answer 1

a) ΔABC ≈ ΔAMN

AM/AB = MN/BC

2/7 = MN/14

7MN = 2×14

7MN = 28

MN = 28/7 = 4 cm

lm = (B+b)/2 = (14+4)/2 = 18/2 = 9 cm

b) ΔABC ≈ ΔAMN

AM/AB = MN/BC = AN/AC

2/7 = MN/10,5 = 3/AC

2/7 = MN/10,5

MN = 21/7 = 3 cm

2/7 = 3/AC

AC = 21/2 = 10,5 cm

NC = AC - AN

NC = 10,5 - 3 = 7,5 cm

P = MB+BC+CN+NM

P = 5+10,5+7,5+3 = 26 cm

Answer 2

a)MN || BC=>(Teorema fundamentala a asemanarii):AM/AB=MN/BC=>MN=BC*AM/AB=14*2/7=4 cm

Fie Q∈MB

MQ=QB

W∈NC

NW=WC

QW->linie mijlocie a trapezului MNCB

QW=(BC+MN)/2=(14+4)/2=18/2=9 cm

b)

MB=AB-AM=7-2=5 cm

MN || BC=> (Teorema fundamentala a asemanarii):AM/AB=AN/AC=>AC=AB*AN/AM=7*3/2=21/2=10,5  cm

NC=AC-AN=21/2-3=15/2=7,5 cm

MN || BC=>(Teorema fundamentala a asemanarii):AM/AB=MN/BC=>MN=BC*AM/AB=10,5*2/7=3 cm

P=BC+CN+NM+MB=10,5+7,5+3+5=26 cm