Pentagonal pyramid

Find the volume and surface of a regular pentagonal pyramid with a base edge a = 12.8 cm and a height v = 32.1 cm.

Correct answer:

V =  3016.1483 cm3
S =  1347.0581 cm2

Step-by-step explanation:

a=12.8 cm v=32.1 cm n=5  S1=41 5 (5+2 5) a2=41 5 (5+2 5) 12.82281.883 cm2  V=31 S1 v=31 281.883 32.1=3016.1483 cm3
S1=n A T=S1/n=281.883/556.3766 cm2  T=2a h1  h1=a2 T=12.82 56.37668.8088 cm  h22=v2+h12  h2=v2+h12=32.12+8.8088233.2867 cm  S2=2a h2=212.8 33.2867213.035 cm2  S=S1+n S2=281.883+5 213.035=1347.0581 cm2



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Showing 2 comments:
#
Sebf
Perfect!
Thanks for demonstration
Really thanks
Sébastien

#
Sebf
I think we should see all the variables, I mean : a, v, n S1, S2 and all the things used to finally get the result S. On the scheme.
I understand the way you calculate on your savant literature. But I 'm sure i' m not the only one who would like to learn about this science visually.
For me it's OK. But I cannot share that.
Very sad while it is very clever.
Please explain how you get the result visually on the scheme.

Thanks by advance

Regards

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