6.1 Use Properties of Tangents. Vocabulary. A circle is the set of all points in a plane that are equidistant from a given point called the center of the circle. A radius is a segment whose endpoints are the center and any point on the circle. Vocabulary.
**Remember we know that the radius is perpendicular to the tangent**
This makes a RIGHT triangle!
So we can use Pythagorean theorem to solve for r.
P. 186 #1, 9-11, 12-20even