Calculating the Volume of a Concave Lens Using Multiple Integration

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SUMMARY

The volume of a circular concave lens with a radius of 2 units and two refracting surfaces defined by the equations z=1/2(x²+y²+1) and z=-1/2(x²+y²) can be calculated using multiple integration. The volume is determined by integrating the height difference between the two surfaces over the area of the lens in the xy-plane. The area of the circular region is π(2²) = 4π, and the height difference between the surfaces is 1 unit. Therefore, the volume of the glass is V = Area × Height = 4π × 1 = 4π cubic units.

PREREQUISITES
  • Understanding of multiple integration techniques
  • Knowledge of polar coordinates
  • Familiarity with the equations of surfaces in three-dimensional space
  • Basic geometry of circles and areas
NEXT STEPS
  • Study the application of polar coordinates in multiple integrals
  • Learn how to set up and evaluate triple integrals
  • Explore the concept of volume under surfaces in calculus
  • Review the geometric properties of concave lenses
USEFUL FOR

Students preparing for calculus exams, particularly those focusing on multiple integration and geometric applications, as well as educators teaching advanced calculus concepts.

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Homework Statement



A circular concave lens of radius 2 units, has two refracting surfaces described by z=1/2(x2+y2+1) and z=-1/2(x2+y2) What is the volume of the glass?


Homework Equations



Over a region R: V=[tex]\int\int\int dA[/tex]


The Attempt at a Solution



I have no idea how to start this. Polar coordinates, bounded regions I don't know anything apart from the fact that I need to use multiple integration.
 
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A line from [itex]z= (1/2)(x^2+ y^2)[/itex] straight up (parallel to the z axis) to [itex]z= (1/2)(x^2+ y^2+ 1)[/itex] has length 1 so the volume is simply the integral of "1" over the region, in the xy plane, the lens covers. And that is just the 1 times the area of that region! What is the area of a circle of radius 2?
 
The second surface is [itex]z= -(1/2)(x^2+ y^2+ 1)[/itex]. Its negative. Even so, I'm doing this question for an exam on monday out of practise for multiple integrals. So how would you do this using integration?
 

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