- Select the [b]POINT tool (Window 2) [/b]and draw a point [b]B [/b]on line [b]r[/b]. [br]- Select the [b]COMPASS tool (Window 6)[/b]. Then click on [b]B [/b]and[b] A[/b] (it represents the length opening of[br]the compass) and again on [b]B [/b](represent the sharp end of the compass). [br][b]-[/b]Select the INTERSECT [b]tool (Window 3) [/b]and mark points [b]C [/b]and [b]D[/b], which are intersection points between the circle with the line [b]r[/b]. [br]- Select the [b]COMPASS tool (Window 6)[/b]. Then click on point [b]C[/b] and point [b]A[/b] (it represents the length opening of the compass) and again on point [b]D[/b] (it represents the sharp end of the compass). [br][b]-[/b]Select the INTERSECT tool [b](Window 3) [/b]and mark point [b]E[/b], which is the point of intersection of the two circles. -Select the LINE [b]tool (Window 4)[/b] and click on [b]A [/b]and [b]E.[/b] Label this line [b]s[/b]. [br]- Select the [b]SHOW/HIDE OBJECT[/b][b] tool (Window 7)[/b] and hide the circles, points [b]C[/b], [b]D [/b]and [b]E[/b], leaving only[br]the lines and point [b]A.[/b][br]-Select the [b]RELATION (Window 8)[/b] and click on the two lines. What happens when you follow all the steps above? [br]- Select the [b]MOVE tool (Window 1). [/b]Move either point [b]A[/b] or line [b]r[/b]. What can you see?

- Select the [b]COMPASS tool (Window 6)[/b]. Then click on the segment [b]AB [/b](it represents the length opening of the compass) and on [b]E [/b](represents the sharp end of the compass). [br]- Select the[b] INTERSECT tool (Window 3) [/b]and mark[b] F and G[/b]. They are points of intersection of the circle with the line. [br]- Select the [b]COMPASS tool (Window 6)[/b]. Then click on point [b]F [/b]and point[b] G[/b] (it represents the length opening of the compass) and again on point [b]F [/b](it represents the sharp end of the compass). After that, click on point [b]G [/b]and point[b] F[/b] (it represents the length opening of the compass) and again on [b]G[/b] (it represents the sharp end of the compass). [br][b]- [/b]Select the [b]INTERSECT tool (Window 3)[/b] and mark a point [b]H[/b], point of intersection of the last two circles.  [br]-Select the [b]LINE tool (Window 4)[/b] and click on point [b]E [/b]and point [b]H[/b]. The intended perpendicular line will appear. Let us analyse it. [br][b]- [/b]Select the [b]INTERSECT tool (Window 3)[/b] and mark point [b]I[/b], point of intersection of points [b]h [/b]and [b]g[/b].  [br][b]-[/b] Select the [b] ANGLE tool (Window 9)[/b]. Click on points [b]E[/b],[b] I [/b]and[b] C[/b] to mark the angle [b]EIC[/b] (the vertex of the angle will always be the second point clicked). What is the measurement of this angle? [br]- Select the [b]SHOW / HIDE OBJECT tool (Window 7)[/b] and hide the circles, points [b]H[/b], [b]F [/b]and [b]G[/b], leaving only the lines and point [b]E.[/b] [br]-Select the [b]RELATION tool (Window 8)[/b] and click on the two lines. What happens when you follow all the steps above? [br]- Select the [b]MOVE tool (Window 1). [/b]Move either point [b]E[/b] or line [b]g[/b]. What can you see?