[b]To draw a straight line from any point to any point.[br][br][/b]A line can be drawn between any two points. On a piece of paper, draw two points, you can always connect those two points together with a line.

In the applet below, use the [icon]/images/ggb/toolbar/mode_join.png[/icon] line tool to connect A to B.[br][br]Use the [icon]/images/ggb/toolbar/mode_segment.png[/icon] segment tool to connect A to C.[br][br]Use the [icon]/images/ggb/toolbar/mode_ray.png[/icon] ray tool to connect B to C.[br][br]Once you have drawn those lines, mark the intersections of your lines with the red line by using either the [icon]/images/ggb/toolbar/mode_point.png[/icon] or [icon]/images/ggb/toolbar/mode_intersect.png[/icon] tools. Using [icon]/images/ggb/toolbar/mode_point.png[/icon] you can just click on the intersection or using [icon]/images/ggb/toolbar/mode_intersect.png[/icon] you can click on the lines and it will mark the intersection for you.[br][br]Play around with these tools until you are comfortable with them