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.
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