Question

Un trunchi de con circular drept are R=12cm,h=8cm si g=10cm.Calculati:
a)r
b)Al
c)V

Answer 1

a)  h²+(R-r)²=G²
8²+(12-r)²=10²
64+(12-r)²=100
(12-r)²=100-64
(12-r)²=36
12-r=√36
12-r =6
-r=6-12
-r = -6  |*(-1)
r =6 cm

b)Al=π(R+r)*G= π(12+6)*10= π18*10=180 π
Al=180π cm²

c)V=$\frac{ \pi h}{3}$*(R²+r+R*r)
V=$\frac{8 \pi }{3}$*(12²+6²+12*6)
V=$\frac{8 \pi }{3}$*(144+36+72)
V=$\frac{8 \pi }{3}$*252
$V= \frac{2016 \pi }{3}$
V=672π cm³