1.
notam coarda AB
notam PN distanta de la punctul P la coarda AB
triunghiul AOB echilateral ⇒ ON=AB√3/2=12√3/2=6√3 cm
teorema lui Pitagora in triunghiul dreptunghic PON
PN=√[6²+(6√3)²]=√(36+108)=√144=12 cm
2.
E= 1/(x+1)+1/(1-x)+2/(x² -1) ,unde x≠+1si x≠-1
E=1/(x+1)+1/(1-x)+2/(x² -1)=1/(x+1)-1/(x-1)+2/(x² -1)=
=(x-1-x-1+2)//(x² -1)=0
raspuns corect c. 0