Castle model

The castle model has a cone-shaped roof. The cone side is 45 cm long, and the base radius is 27 cm.
a) What is the roof volume?
b) How many dm2 of wallpaper is used to glue the roof, i.e., the cone shell?
c) What is the weight of the roof if it is made of wood with a density of 0.56 g/cm3?
  They were rounded to tenths of a kilogram.

Correct answer:

V =  27482.6525 cm3
S =  38.1704 dm2
m =  15.4 kg

Step-by-step explanation:

s=45 cm r=27 cm  h=s2r2=452272=36 cm  V=31 π r2 h=31 3.1416 272 36=27482.6525 cm3=2.748104 cm3
S1=π r s=3.1416 27 453817.0351 cm2 S=S1 dm2=S1:100  dm2=3817.0351:100  dm2=38.17 dm2=38.1704 dm2
ρ=0.56 g/cm3 m1=ρ V=0.56 27482.652515390.2854 g  m=m1 kg=m1:1000  kg=15390.2854:1000  kg=15.4 kg=15.4 kg

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