Ice-Cream Cone problem - Volume in Spherical Coord

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Homework Help Overview

The problem involves calculating the volume of a solid bounded by a cone and a sphere using spherical coordinates. The sphere is defined by the equation x² + y² + z² = 10z, and the cone is described by z = √(3(x² + y²)). The dimensions provided include a radius for the sphere and a total height for the solid.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to find the angle phi by substituting values into the cone's equation and calculating the corresponding z value. They express the integral setup for volume calculation in spherical coordinates. Other participants question the choice of providing a decimal approximation instead of an exact answer, suggesting a preference for exact values in mathematical expressions.

Discussion Status

The discussion is ongoing, with participants providing feedback on the integral setup and discussing the format of presenting answers. There is no explicit consensus on the best approach to presenting the final answer, but guidance on providing exact values alongside approximations has been offered.

Contextual Notes

Participants note a preference for decimal answers based on past experiences with instructors, which may influence how they present their solutions.

masterchiefo
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Homework Statement


S is the sphere of equation x2 + y2 + z2 = 10z and C the cone of equation
z= sqrt(3*( x2 + y2)) . The axes are measured
centimeters.
R of sphere = 5
D = 10

Total height is 10 cm

Illustrate the solid E bounded by the C cone and the sphere S and calculate its volume using the details
Spherical.

Homework Equations

The Attempt at a Solution


To find phi:
x=0
z= sqrt(3*( x2 + y2))
z= sqrt(3*( 02 + y2))
z= y*sqrt(3)

y= 3 <== I picked 3, could of picked any number, its just to find the Z and then find the angle.
z= 3*sqrt(3)

tan(phi)=3/(3*sqrt(3))
phi = pi/6 ===30degree

Theta = 2*pi

$=integral
2*pi$0 pi/6$0 10*cos(phi)$0 p2*sin(phi) dp dphi dtheta

229.074cm3
 
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I didn't check the value of your integral but it looks like it is set up correctly. Why give a decimal instead of exact answer?
 
LCKurtz said:
I didn't check the value of your integral but it looks like it is set up correctly. Why give a decimal instead of exact answer?
I am used to give decimal as my teacher always ask for that.
 
LCKurtz said:
I didn't check the value of your integral but it looks like it is set up correctly. Why give a decimal instead of exact answer?

masterchiefo said:
I am used to give decimal as my teacher always ask for that.

Nevertheless, what you should routinely do is give the exact answer if it is practical, and at the very end put the decimal approximation. For example, if the exact answer is ##\frac {\sqrt 3} 5## you could write it like this:
$$\text{Your Variable }=\frac {\sqrt 3} 5 \approx .3464$$That would be correct, good form, and would satisfy your teacher.
 

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