Question

A cone with base diameter of 60m and height of 45m is given. For the volume calculation purposes of the cone, it is approximated via an inscribed regular decagonal pyramid (number of base edges is ten). Find the percent error of this volume

Answer 1

area of a regular n-gon is 1/2 nr^2 sin(2π/n)
You have r=30, so
Vc = 1/3 πr^2h
Vp = 1/2 nr^2h sin(π/5)
so, the % error is (Vc-Vp)/Vc