Question

Un trunchi de con circular drept are At=1890pi cm patrati,R=25cm si r=15cm.Calculati:
a)Al
b)h
c)V

Answer 1

a)
At=Al+AB+Ab
AB=πR²=π25²=π625
Ab=πr²=π15²=π225
Al+625π+225π=1890π
Al+  850π=1890π
Al=1890π-850π
Al=1040π
b)Al=π(R+r)*G
π(25+15)*G=1040π
40πG=1040π  |:40π
G=26 cm
h²+(R-r)²=G²
h²+(25-15)²=26²
h²+10²=676
h²+100=676
h=√576
h=24 cm
c)V$\frac{ \pi h}{3}$(R²+r²+R*r)
V=$\frac{24 \pi }{3}$(25²+15²+25*15)
V=8π(625+225+375)
V=8π*1225
V=9800π cm³