Cylinder in Sphere: Volume Calculation | Max Vol.

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SUMMARY

The discussion focuses on calculating the maximum volume of a right circular cylinder inscribed in a sphere with a radius of 10 cm. The height of the cylinder is derived using the formula \( h = 2\sqrt{100 - r^2} \), where \( r \) is the radius of the cylinder. The user also explores a similar problem involving a cylinder inscribed in a cone with a height of 3 m and a base radius of 3 m, ultimately determining that the maximum volume of this cylinder is \( 4\pi \) cubic meters.

PREREQUISITES
  • Understanding of geometric shapes, specifically spheres and cylinders
  • Knowledge of the Pythagorean theorem
  • Familiarity with volume formulas for cylinders
  • Concept of similar triangles in geometry
NEXT STEPS
  • Study the derivation of volume formulas for cylinders and spheres
  • Learn about optimization techniques in calculus for maximizing volumes
  • Explore the relationship between inscribed shapes and their enclosing shapes
  • Investigate the properties of similar triangles and their applications in geometry
USEFUL FOR

This discussion is beneficial for students studying geometry, particularly those tackling optimization problems involving inscribed shapes, as well as educators looking for practical examples to illustrate these concepts.

skateza
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Homework Statement


Find the volume of a right circular cylinder of maximum volume that can be inscribed in a sphere of radius 10cm.


I'm using this problem to help me solve a similar one with a cylinder inside a cone, now what I'm not sure about is, in the answer book they say, Let the radius of the cylener be r cm, 0 < r< 10. Then the height is 2sqrt(100-r^2)
... where did they get this height from?
 
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Draw a picture. "Seen from the side", the sphere is a circle with radius 10. Now draw a "cylinder" (i.e. a rectangle) in the "sphere" (circle). If the radius of the cylinder is r, then the base length of the rectangle is 2r. Let h be the height of the cylinder (rectangle) and draw a diagonal. What is the length of the diagonal? Can you use the Pythagorean theorem to write h as a function of r?
 
okay with that i still can't figure out my peoblem. Here is the question i am really trying to solve. A right cirular cylinder is inscribed in a cone with height 3m, and base radius 3m. Find the largest possible volume of such a cylinder.

V = (pie)r^2h, how would i find the height in this casE?
 
Okay i think i got it, is this right:

Drawing a side diagram with a triangle and a rectangle in the middle i can use similar triangles to show cos(Theta) = h/(3-r) = 1; therefore h = 3-r

Using this i get a maximum value of 4pie
 
Looks right!
 

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