Volume and plane intersecting sphere

AI Thread Summary
A plane tangent to a sphere is tilted at an angle theta, causing it to intersect the sphere and divide its volume into two regions. The volume of the hemisphere created by this intersection can be expressed using a specific equation involving theta. To prove this volume calculation, integration of the sphere's sections is suggested as a method. However, there is a discussion about the need for a geometric proof, particularly for those without calculus knowledge. Understanding the relationship between the plane's angle and the sphere's volume is crucial for solving the problem.
FortranMan
Messages
30
Reaction score
0

Homework Statement



A plane is tangent to the surface of a sphere. You then tilt the plane at an angle theta along one axis, causing it to begin passing through the sphere and splitting the sphere's volume into two regions. I claim the volume of the hemisphere the plane has just passed through is found from the equation below. How do I prove this using geometry?

Homework Equations



<br /> V = \frac{\pi R^{3}}{3}( cos^{3}(\theta) - 3 cos(\theta) + 2 )<br />

The Attempt at a Solution

 
Physics news on Phys.org
Attach a picture please, to show what theta is.

ehild
 
You prove it with integration of the sphere sections.
I'm not sure what d'you mean "geometrically".
 
Quinzio said:
You prove it with integration of the sphere sections.
I'm not sure what d'you mean "geometrically".
I think he meant geometrically because he has not yet a working knowledge of calculus since this is in the precalculus section.
 
I picked up this problem from the Schaum's series book titled "College Mathematics" by Ayres/Schmidt. It is a solved problem in the book. But what surprised me was that the solution to this problem was given in one line without any explanation. I could, therefore, not understand how the given one-line solution was reached. The one-line solution in the book says: The equation is ##x \cos{\omega} +y \sin{\omega} - 5 = 0##, ##\omega## being the parameter. From my side, the only thing I could...
Essentially I just have this problem that I'm stuck on, on a sheet about complex numbers: Show that, for ##|r|<1,## $$1+r\cos(x)+r^2\cos(2x)+r^3\cos(3x)...=\frac{1-r\cos(x)}{1-2r\cos(x)+r^2}$$ My first thought was to express it as a geometric series, where the real part of the sum of the series would be the series you see above: $$1+re^{ix}+r^2e^{2ix}+r^3e^{3ix}...$$ The sum of this series is just: $$\frac{(re^{ix})^n-1}{re^{ix} - 1}$$ I'm having some trouble trying to figure out what to...
Back
Top