2) in ΔA'AB ⇒ TP⇒ A'A²= A'B²-AB²⇒
A'A²= 25-16=9⇒ A'A=3cm
3)
AB=4 cm⇒ R=2cm ; AA' = G = 3cm
At= Al+ 2*Ab
Al= 2πRG = 2π*2*3=12π cm²
Ab=πR² = 4π cm²
At= 12π+2*4π = 12π+8π=20π cm²
V=Ab*h= πR²G= π*4*3=12π cm³
4)
Lungimea arc AB= Lungime semicerc= πR=2π= 2*3,14=6,28cm
Lungime drum = 6,28² + B'B² =39,43 + 9= 48,43⇒
Lungime drum = √48,43 < √49 (= 7)
