Video Transcript
What is the projection of 𝐷 on
line 𝐴𝐶?
When we think about projections,
the first thing we wanna identify is our target line, the line on which our
projection will fall. In this case, that’s the line
𝐴𝐶. We say that 𝐴𝐶 is our target
line, and we want to project the point 𝐷 onto this target line. To do that, we need to consider a
perpendicular line to our target line that intersects the point we want to make a
projection of.
Helpfully, we see here that line
segment 𝐸𝐷 is perpendicular to the line 𝐴𝐶. If we imagine this perpendicular
line as a light source, the projection of 𝐷 onto 𝐴𝐶 will be the shadow of 𝐷 onto
line 𝐴𝐶. And the shadow of this point will
be another point. In this case, it’s going to be the
point 𝐸. The point 𝐸 is the place of the
intersection of the perpendicular line 𝐷𝐸 onto 𝐴𝐶.
And so, we can call the point 𝐸
the projection.
