solid of revolution

tpgettys shared this question 2 years ago

I would like to first show the area under the graph of y=sqrt(x) between 1 and 4 (y>0), then show the solid of revolution about the x-axis, preferably using a slider for the angle of revolution. How might that be done?

Comments (2)


Define a function f(x)= If(1 ≤ x ≤ 4, sqrt(x)) a slider 'angle'.

Then you show the solid of revolution with the command Surface(f, angle, xAxis)

You could show just the upper (positive) part while limiting the range of the slider



I use a trick to show the rotating trapezoid ;)

First, create the trapezoid, say trap:

Surface(t, u f(t), 0, t, 1, 4, u, 0, 1)
where 1, 4 are the interval bounds, then I rotate it:

Rotate(trap, α, xAxis)

and activate the trace for it.

© 2020 International GeoGebra Institute