# Learnosity evaluation.

I am trying to create an applet for construction of tangents and I was wondering how would I be able to evaluate segments or points which have not been defined yet.

My question is to draw a circle of r=6cm with center O and construct tangents from a point that is 10cm away from the center. So, in this case, my steps are as follows, I give the student an applet with a customized toolbar with tools like intersect, point, perpendicular bisector and circle using two points.

Steps are

1) Construct the circle of r=5 with center O and mark an external point A at 10cm

2) join OA and construct a perpendicular bisector 'g' which intersects OA at B.

3) With B as center and OB as radius construct a new circle.

4) Marks the points of intersection as P and Q and join AP and AQ to attain the tangents.

How can I evaluate if the student has drawn tangents AP and AQ without restricting their choice of A and letting them do the entire construction? Please let me know if you have a solution for this

It's possible but not easy (the principle is simple, but the needed commands are tricky).

See the comments in the button-script "check construction"

There exist also a button with JS. But this button you must never change, so you can handle it as BlackBox.

If you want change the sample then change the reed and green objects (given basis-objects, target-objects).

I'm able to answer to specific questions (when you had create new application, please. send also ggb-file)

If you have errors: please send the ggb-file and a short description.

Here's an example of how to do that quite flexibly by just specifying hidden "target" objects in a list.

(the JavaScript will need moving into "Global JavaScript" though. Please email me for further support (michael at geogebra dot org)

http://test.geogebra.org/~m...

Thanks, but sorry, I see only this (after 5 min I have closed):

I see it fine win7 firefox,opera,chrome

great work

but if a target is deleted the console is not refreshed

Sure, it's just a "getting started" example :)

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