Instructions for constructing an altitude.
The circles represent the arcs.
Create the intersections that you see here.
Sometimes you will need to extend the the segment (red
line).
Start with an arc from the vertex "C" though line "AB" to create the
intersections at "D" and "F" (green circle).
With center "D" and radius "DF", construct an arc (blue
circle).
Again with center "F" and radius "FD", construct and arc (Yellow
circle).
Note the intersection of the blue and Yellow
circles
"G".
Connect the ponts "C" and "G" to complete the altitude.
Hahoo!
You have constructed an altitude.
Now try to do the same thing to another side.