Using either your tools or just freehand, can you draw a triangle with a circle that fits perfectly inside (touches each side exactly one time)?

I can use a compass and straight edge to draw a circle inscribed in a triangle, and a circle circumscribed around a triangle.

Find the perpendicular bisector of each side of the triangle.

The intersection of these points is the center of the circle. The radius (compass setting) is the distance from the center to any corner of the triangle.

Put the point on the center, set the pencil on one of the corners, draw the circle.

Check out this animation.

Draw the angle bisector of all three corners of the triangle (you actually only need 2, though).

Where the bisectors meet is the center of the inscribed circle.

To set your compass, you need to know where the circle touches one of the sides. This happens (on each side) where a perpendicular line passing through the center crosses the side. Find one of these to set your compass, then draw the circle!

Check out this animation.

For tomorrow's quiz (and other things), you need to know:

• How to draw perpendicular bisectors

• How to draw angle bisectors

• How to draw a perpendicular line through a point on the line

• How to draw a perpendicular line through a point not on the line

• How to draw a circle inscribed in a triangle

• How to draw a circle circumscribed around a triangle

Work with a partner to create a set of notes that you can use to remember each of these processes. Consider some combination of steps and an example drawing.

For your work today:

For a 3, complete this worksheet.

For a 4, use these skills to create a logo for your soon-to-go-viral Instagram. It better be good!