![](https://cdn.geogebra.org/resource/t6wjbfq8/FnZmFcm7TYBLGnBS/material-t6wjbfq8.png)
Cup Modeling (1)
Your task: Create a virtual model of this cup below. Refer to the "Measure a Radius Accurately" page to help you measure the radius of the top and bottom of this cup.
![](https://cdn.geogebra.org/resource/t6wjbfq8/FnZmFcm7TYBLGnBS/material-t6wjbfq8.png)
Before building in the 3D app below, you will need to measure the following:[br][list][*]Bottom radius of this cup[/*][*]Top radius of this cup[/*][*]Height of this cup[/*][/list][br]The height of this cup should be fairly easy to measure. Please refer to the [b]reference[/b] section (left) to see how to measure a radius of this cup accurately. [br]
Once you get your data, build a virtual model of this cup below. Be sure to watch the quick silent YouTube video below that illustrates how to create a surface of revolution.
How to Create a Surface of Revolution in GeoGebra 3D Calculator (quick silent demo)
Go to the [b]MENU[/b] (3 horizontal bars upper left corner). Go to [b]SAVE[/b]. Title it [b]Cup Model 1[/b]. Open this in GeoGebra 3D Calculator on you phone or tablet to test how well the virtual model fits over the real one. [br][br]If you forget how to do this, do the following: [br][list][*]Sign in to your GeoGebra account on Safari if you have an iPhone or iPad[/*][*]Sign in to your GeoGebra account on Chrome if you have an Android or other non-iOS tablet. [/*][*][url=https://youtu.be/_gjrdrqADZM?t=142]Follow the instructions seen here[/url]. (No need to watch the beginning of the video.)[/*][/list]
Measure a Radius Accurately
In this cup or bowl modeling project, it is important you measure the radius of both top and bottom circular openings accurately. [br][br]Please follow these steps to do so.
Trace the opening of the circular cup or bowl on a piece of paper.
![](https://cdn.geogebra.org/resource/fh5pt2ym/SN9Rg2EoGT9RFPP1/material-fh5pt2ym.png)
Plot two points A and B anywhere on the circle.
![](https://cdn.geogebra.org/resource/ecwud997/wHdIgS4EBTKuUpOZ/material-ecwud997.png)
Fold point A directly on top of point B. Crease sharply. Then unfold.
![](https://cdn.geogebra.org/resource/jv4e2cnu/eLw5Zo7FdZXwf9UJ/material-jv4e2cnu.png)
Plot two new points C and D on the circle.
![](https://cdn.geogebra.org/resource/gmvv2hww/OfbLOqhZuWmFefJD/material-gmvv2hww.png)
Fold point C directly on top of point D. Crease sharply. Then unfold.
![](https://cdn.geogebra.org/resource/dedrxtvy/NFTJJC6aiaIH3oFk/material-dedrxtvy.png)
Note where your two fold lines intersect. This is the center of your circle. You can now easily measure its radius.
![](https://cdn.geogebra.org/resource/meryqs4y/GUGGZPkuETZhYmaH/material-meryqs4y.png)