[size=200][b]Draw a line called "s" perpendicular to the line "r" that runs through point "P"[/b][/size][br][br][color=#000000]Two secant lines are perpendicular if they define 4 right angles.[/color][br][br][color=#9900ff]1st. Activate the "Perpendicular line" tool [icon]/images/ggb/toolbar/mode_orthogonal.png[/icon] and then click on line "r" and point "P".[/color][br][br][color=#9900ff]2nd. Name "s" the perpendicular line.[/color][br][br][color=#000000]The two curved arrows located in the upper right corner of the Graphics View allow you to reset the activity.[/color][br][color=#000000]If the activity is correct, you will get 10 points automatically.[/color]