# combine by dragging (1)

## introduction

Another way to combine graphs and equations is a dragging exercise. Each equation has to be dragged to an answering rectangle under the according graph. A control button resets each wrong positioned equation to its initial position. A reset button resets all.

## How it is done?

The control is based on the position of the lowerleft corners of the yellow and the white rectangles. If AAA = AA the yellow rectangle is dragged to the proper position and the combination is right. If not, you made a wrong combination. Set he point capture style must be fixed to grid to avoid rounding.
• 4 points: Create 4 points an posotion them according to the dimensions of your screen.
• 3 vectors: create the vectors a to define the dimensions of the rectangles and the width of the pictures.
• 4 pictures: - Define 4 functions and export the graphs as a picture. - Insert the picture of the first graph. - Define as the `lowerleft corner = AA + w `and as the `lowerright corner = AA + u+w` - Do likewise for the other pictures.
• 4 white rectangles: - Define the white rectangle under the first graph as `Polygon(AA, AA + u, AA + u + v, AA + v)` - Do likewise for the other three.
• 4 yellow rectangles: - Define the points AAA, BBB, CCC and DDD - Define the yellow rectangle `Polygon(AAA, AAA + u, AAA + u + v, AAA + v)` - Do likewise for the points BBB, CCC and DDD - Create four texts with the equations and attach them to AAA, BBB, CCC and D. - Now: Ensure in the Properties that the only objects you can select are these four yellow rectangles.
• contol button: A button checks the answers with following script: ```SetValue[AAA,If[AA!=AAA,(-12,-7),AA]] SetValue[BBB,If[BB!=BBB,(-5,-7),BB]] SetValue[CCC,If[CC!=CCC,(2,-7),CC]] SetValue[DDD,If[DD!=DDD,(9,-7),DD]]```
• reset button: A button resets AAA, BBB, CCC and DDD to their initial position ```SetValue[AAA,(-12,-7)] SetValue[BBB,(-5,-7)] SetValue[CCC,(2,-7)] SetValue[DDD,(9,-7)]```