display a surface of revolution

tpgettys shared this question 1 year ago
Answered

So, I have z=x^2+y^2 (paraboloid), and the planes z=2 and z=4, and would like to show only the surface of the paraboloid between 2 and 4. Is there an intersection command for regions or something for this?

Comments (3)

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solids of revolutions can be displayed in GeoGebra as parametric surfaces with the command:Surface( <Expression>, <Expression>, <Expression>, <Parameter Variable 1>, <Start Value>, <End Value>, <Parameter Variable 2>, <Start Value>, <End Value> ).

So you can use Surface(sqrt(h)*cos(α), sqrt(h)*sin(α), h, h, 2, 4, α, 0°, 360°)

chris

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or If(2 ≤ x² + y² ≤ 4, x² + y²)

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Excellent! Thank you both for the quick and helpful replies.

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