Perpendicular Line Through a Point
Basic Construction 3
We would now like to draw a perpendicular line through a point that is not the midpoint, which is actually extremely similar to what we just did! Once we learn this BC, we will unlock a knew tool.
Tool Practice
Now that we have learned how to draw a perpendicular bisector, we have unlocked the perpendicular bisector tool
and the midpoint tool 
! We will practice this now.
In the applet below, find the perpendicular bisector tool 
, click on A, and then click B; you just just drawn a perpendicular bisector like we did in BC2, but much quicker.
We can also find the midpoint of a line using the midpoint tool 
, click D, and then click F; you just found the midpoint of the line! Using these two tools, you can quickly find these features of lines and even if you move the blue points, your new features will adjust to match.
Practice with these tools then move to the second applet for BC 3.
and the midpoint tool ! We will practice this now.
In the applet below, find the perpendicular bisector tool , click on A, and then click B; you just just drawn a perpendicular bisector like we did in BC2, but much quicker.
We can also find the midpoint of a line using the midpoint tool , click D, and then click F; you just found the midpoint of the line! Using these two tools, you can quickly find these features of lines and even if you move the blue points, your new features will adjust to match.
Practice with these tools then move to the second applet for BC 3.Tool Practice
Now for BC 3! Use the tools provided in the applet below to see if you can construct a line through C that is perpendicular to line AB. It is very similar to what we did in BC 2 except we have one of the circle intersections already, C.
Try to figure it out on your own but if you need help, use the video provided.