00:01
All right, friends, let's take a look at this problem together.
00:02
So what we have going on is an angle, and what we are going to do first is to copy the angle, and then we're going to talk about how it relates to a circle and the radius of a circle, specifically.
00:13
So what we are going to do, hopefully you have the first part of this angle drawn, and we're going to look to see where angle or where letter r, or excuse me, letter f is going to be up here somewhere in order to create the angle f, r, t.
00:27
Then what we're going to do is to copy the angle over here with some different letters.
00:31
And then we're going to relate that to the radius of a circle.
00:35
So the way that we use our compass to do this is to take the pointy side of our compass.
00:40
Let me undo that mark really quick.
00:42
There we go.
00:43
We're going to take the pointy side of our compass and we are going to put it on the vertex of the angle.
00:49
And then we are going to move our compass so that the tip of our compass is on the angle, me, on the point that is on the bottom ray of the angle.
01:01
So then once we do that, we're going to take our compass and we are going to open it up just like this.
01:07
And we're going to cross through the other side here.
01:12
And so the way that we're going to do that then, we are going to take our compass away.
01:18
And this is where we are going to put that letter f.
01:22
So right here, this is going to be our letter f.
01:24
Now this is going to help us to copy our angle.
01:28
So my compass right now is already opened up to the same distance from r to t, but we're going to need to use that again.
01:37
So i'm going to police my compass, my pointy side of my compass right here.
01:41
We're going to call this letter c.
01:44
I'm going to call that letter c right here.
01:46
This is going to be the vertex of my other angle.
01:49
And then i'm going to use my compass and i'm going to hold it here.
01:53
Oops.
01:53
There we go.
01:54
Hang on just a second.
01:56
I'm going to bring it down.
01:57
Here and what we're going to do is to mark right here so this is what is going to show us where that marking is so right here this is going to be the same distance so cd let's label this with the d cd is going to be the same length as r t and we know that to be true because we've measured it to be that way so then what we are going to do also to copy this angle is we are going to make this arc even larger because we want to see where it intersects for another part of our angle.
02:36
So i'm going to open this up and we're going to mark all the way like here.
02:42
There you go.
02:43
There's my big angle.
02:45
Now what we need to do is to take our compass and we are going to flip it around the other way.
02:52
And we are going to place the tip of your compass on the letter t.
03:01
Now what i need to do is to measure my angle to match up with point f.
03:10
So i'm going to move my compass here.
03:13
I'm going to stretch it so that it opens up to point f, just like that.
03:18
There we go.
03:19
And now what we can see is we can see this location where it intersects.
03:24
We're going to pick up our compass and we're going to do the that right over here.
03:30
So this is going to be our point d and my compass is already opened up to the same amount.
03:35
So i'm going to cross here.
03:37
And what this shows me, i'm going to take my compass away now over here, set it on the corner of my table.
03:43
And what i see is that i have an intersection point.
03:46
Cool things happen in geometry whenever we have intersection points...