Răspuns:
3. Ip. ABCD-paralelogram
m(CBA) =150°
AB = 40 cm
AD = 18 cm
____________________
m(Â) =180°-150°=30°=>DD=AD/2=18cm/2=9cm
Aabcd = AB - DD =40 cm × 9cm = 360cm²
4. A= d1×d2/2=>A=BD×AC/2
=> A = 48×36/2=>2(24+18)/2
=> A=24+18=>A=42cm²
5. P=72
P=l×4
l=72:4
l=18
A=l×l
A=18×18=324cm²
6. h->este înălțimea
B->baza mare
b->baza mica
(B+b) ×h : 2 = (24+16)×16=320cm²
II. 1. A trapez = (B+b) ×h/2=(AB+CD)×AD/2=
= (24+16)×12/2=40×12/2=20×12=240cm²
2. CB = 2×AM=2×24=48
AD = 48/4=12
48×12/2=288cm²
3. P=2×l+2×L=104cm
l=4/9×L=4L/9
2L+8L/9=104
18L+8L=104×9
26L=936
L=936/26
L=36cm
l=4×36/9=16cm
L×l=36×16=576cm²
4. L=48cm
l=5/12×L=5/12+48=48×5/12=240/12=20m
2×48+2×20=96+40=136
4l=>136=4l=>l=136:4=>l=34
l²=34²=1156cm²
Sper ca te-am ajutat!
Bafta!
