Learning Resources

Investigation 5: Tangent Properties

Steps A & B

Be sure you draw the circles well away from the edge of the paper. When you fold the tangent line at point P, make sure the circle lies on the outside of the fold. This will allow you to determine more easily that the fold touches the circle at only one point.

Step C

The angle that the radius makes with the tangent line should be 90°. If you did not obtain this, check both the position of your radius and the accuracy of your fold lines.

Step D

Fold another tangent line at a second point, Q, on the circle. Make sure that the two tangent lines are not parallel to each other. Otherwise, they will not intersect.

Step E

The conjecture is contained on the summary page at the end of the lesson.

Steps F & G

Mark the point of intersection of the two tangent lines and measure the distance from this point to the points of tangency on the circle.

Step H

The conjecture is contained on the summary page at the end of the lesson.