Va rog exercițiul 8 complet

Va Rog Exercițiul 8 Complet class=

Răspuns :

Al=pi*r^2/4=3,14*10^2/4=3,14*100/4=314/4=78,5 cm^2

Al=pi*rb*G=3,14*r*V100-r^2=78,5

r*V100-r^2=78,5/3,14=25

ridic la patrat 
r^2(100-r^2)-25^2=0
100r^2-r^4-625=0 | *(-1)
r^4-100r^2+625=0

r^2= (100+V10000-2500)/2=(100+V7500)/2=(100+50V3)/2=50+25V3