1. Radius drawn to a tangent
forms a right angle.
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia Activities from Patty Paper® Geometry by Michael Serra

2. Draw a circle with the Solo cup.
Steps:
Draw a circle with the Solo cup.
Use your straightedge to draw a line that appears to be tangent to your circle.
Fold to find the center.
Draw a line between the center and the point of tangency.
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia Activities from Patty Paper® Geometry by Michael Serra

3. Steps:
Place the corner of another piece of patty paper at the angle formed between the diameter and the tangent.
What do you know?
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia Activities from Patty Paper® Geometry by Michael Serra

4. same external point are ≅.
Two tangents from the
same external point are ≅.
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia Activities from Patty Paper® Geometry by Michael Serra

5. Draw a circle with the Solo cup. Make a point outside of the circle.
Steps:
Draw a circle with the Solo cup.
Make a point outside of the circle.
Draw 2 tangent lines from the point to the circle.
Mark the points of tangency.
Fold one tangent onto the other to compare their lengths.
What do you know?
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia Activities from Patty Paper® Geometry by Michael Serra