Question

Ex 25 din atașament va rog

Answer 1

a) fie CM_|_AB =>CM=AD=9

BM=AB-CD=20-8=12

In ΔCMB

CB²=BM²+CM²=12²+9²=144+81=225

CD=15

Perimetru trapez=AB+BC+CD+AD=10+15+8+9=52 cm

Aria trapez= (AB+DC)*AD:2= 126 cm²

b) Notam AN distanta de la A la latura BC=> AN_|_BC

in ΔABC avem:

CM*AB=AN*CB

9*20=AN*15

AN=9*20:15

AN=12

c)in ΔEAB

ED/EA=CD/AB

ED/(ED+AD)=8/20

ED/(ED+9)=2/5

5*ED=2*ED+18

3*ED=18

ED=6

EA=AD+ED=6+9=15

Aria ΔEAB=EA*AB:2=15*20:2=150 cm²