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### Course: Geometry (FL B.E.S.T.)>Unit 8

Lesson 9: Constructing circumcircles & incircles

# Geometric constructions: triangle-circumscribing circle

Sal constructs a circle that circumscribes a given triangle using compass and straightedge. Created by Sal Khan.

## Want to join the conversation?

• How do you delete compasses and straight edges in the program?
• Hi there,

You can delete a single circle (compass) or a single segment (straightedge) in this exercise. The only option now is to click Clear to delete all of them.
• Would it be the same to bisect all the angles at , instead of the sides?
(1 vote)
• Does it matter where you put the straightedges to line it up to the triangle?
• untill and unless you can not get your task completed
• Does the size of the compasses used to find the bisector matter? Or can you use any size?
• They need to have a radius equal to at least half of the triangle's side length. In addition, each compass needs to be the same size.

However, so long as you meet those requirements, they can be as big as you want.
• How does he know that what he does starting at will make the correct perpendicular bisector?
• He would plan ahead ofc
(1 vote)
• Why doesn't this seem to work with obtuse triangles?
I'm assigned to circumscribe an obtuse triangle, but it doesn't seem to be possible.
• can you please explain more
• Can we solve this question by finding the intersections of angle bisector like how Sal Khan did in (circle inscribing triangle) ?