Question

1. Un trunchi de con circular drept are R=17cm, r=5cm si G=20cm. Calculati:
a) h
b) Al
c) V

2. Un trunchi de con circular drept are R=9cm; G=5CM si h=4 cm. Calculati:
a)r
b) Al
c) V

Answer 1

1. Un trunchi de con circular drept are R=17cm, r=5cm si G=20cm. Calculati: a) h
R-r=17-5=12
h=√(20²-12²)=√(400-144)=√256= 16 cm
b) Al=πg(R+r) =π×20×(17+5)=440π cm²
c) V=πh(R²+r²+Rr)/3=π×16(17²+5²+17×5)/3=π×16(289+25+85)/3=
=π×16×133=2128π cm³

2. Un trunchi de con circular drept are R=9cm; G=5CM si h=4 cm. Calculati:
a)r
R-r=√(5²-4²)=√(25-16)=√9= 3 cm
r=9-3=6 cm
b) Al =πg(R+r) =π×5×(9+6)=75π cm²
c) V=πh(R²+r²+Rr)/3=π×4(9²+6²+9×6)/3=π×4(81+36+54)/3=
=π×4×57=228π cm³