Geometry Refresher Proportional Triangles Explained Simply!

Added: 2026-05-22

[00:00:00]All we know is about this 8-2-100 ft relation here.

[00:00:09]Do you remember proportions of triangles?

[00:00:17]I think I forgot it.

[00:00:20]Hm?

[00:00:22]Um like 30-60-90?

[00:00:29]Oh, you're thinking trig space. This is before trig space.

[00:00:33]Left field.

[00:00:36]Proportional triangles. I think I just taught this to one of my like seventh, eighth graders.

[00:00:40]If we're basically talking about a triangle here, and this is probably, again, left field completely.

[00:00:47]And we want to compare the small triangle of 100 ft to 8 versus what we're trying to do with this 10 thousand not drawn to scale larger triangle just for effect.

[00:01:10]So, wait, it's 10,562 what? What do we put on the height?

[00:01:16]Um 8 ft?

[00:01:20]Not necessarily cuz it should rise every 100.

[00:01:26]So, do we know how much it's risen? In fact, that's how much we're trying to find. How much did it go up that road? How far above ground is it now after it's traveled 10,560 mi?

[00:01:45]So, do we actually know on the larger triangle the height?

[00:01:54]Call it a variable X, unknown.

[00:01:58]We can use that though. So, here's how proportional triangles works.

[00:02:03]We basically take a relation, set them equal to each other. We got a left triangle, right triangle.

[00:02:10]You say, "All right.

[00:02:12]We know the left side is 8 by 100.

[00:02:16]What's the right side?"

[00:02:18]X over 10 5 560.

[00:02:22]Yeah, we're just matching the heights on the same numerator. We can reverse it if we wanted to.

[00:02:30]But, doesn't matter which direction we actually write it. I actually prefer X on top like this because I don't have to like move it around too much. And then we match