Al=60
Al=Pb*h Pb*h=60
At=78
At=Al+2Ab
78=60+2Ab
2Ab=18
Ab=9
Ab=l²=9 l=3
Pb*h=60
4*3*h=60
12*h=60
h=5
ABCD-patrat
DB=l√2= 3√2
DD'_/_(ABC)
DB inclus(ABC) ⇒DD'_/_DB ⇒mas<D'DB=90
ΔD'DB ⇒D'B²=D'D²+DB²=5²+(3√2)²=25+18=43 ⇒D'B=√43
V=Ab*h=9*5=45
2)V=l*L*h=15*11,5*4=690 dm³ nisip