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PROBLEM: "Construct a circle
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circumscribing the triangle."
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So that would be a circle that touches the vertices
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the three vertices of this triangle.
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So we can construct it using a compass
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and a straight edge, or a virtual compass
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and a virtual straight edge.
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So what we want to do is to center the circle
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at the perpendicular bisectors of the sides.
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Or sometimes that's called
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the 'circumcenter' of this triangle.
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So let's do that.
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And so let's think about –
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Let's try to construct where the perpendicular
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bisectors of the sides are.
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So let me put a circle right over here whose radius
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is longer than this side right over here.
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Now let me get one that has the same size.
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So let me make it the same size
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as the one I just did.
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And let me put it right over here.
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And this allows us to construct
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a perpendicular bisector.
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If I go through that point and this point right over here,
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this bisects this side over here,
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and it's at a right angle.
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So now let's do that for the other sides.
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So if I move this over here,
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and I really just have to do it for one of the other sides,
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because the intersection of two lines
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is going to give me a point.
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So I can do it
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for this side right over here.
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Let me scroll down so that you can see a bit clearer.
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So let me add another straight edge right over here.
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so I'm going to go through that point,
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and I'm going to go through this point.
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So that's the perpendicular bisector of
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this side right over here.
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And now I could do the third sided
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and it should intersect at that point.
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I'm not being ultra, ultra-precise.
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But I'm close enough.
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And now I just have to center one of these circles.
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Let me move one of these away.
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So let me just get rid of this one.
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And now I just have to move this circle
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to the circumcenter and adjust its radius so that
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it gets pretty close to touching the three sides,
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the three vertices of this triangle.
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It doesn't have to be perfect.
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I think this exercise has some margin for error.
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But they really want to see that you've made
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an attempt at drawing the perpendicular bisectors
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of the sides, and to find the circumcenter,
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and then you put a circle right over there.