1. Module 15: Lesson 4 Perpendicular Bisectors of Triangles
Vocabulary
The triangle is circumscribed by the circle.
The triangle is inscribed by the circle. A
Think of the words Circumnavigate and inside. B C

2. 3 or more lines that intersect at the same point are said to be concurrent. The point of intersection is called the point of concurrency. The point of concurrency for 3 perpendicular bisectors of a triangle is called the circumcenter (Point G).
Circumcenter Theorem
The perpendicular bisectors of the sides of a triangle intersect at a point that equidistant from the vertices of the triangle.

3. If OF = 7, OB = 25, and AD = 20
Find AO and AC
If AO = 85, OF = 13, and AC = 136
Find CD and BO
If CO = 65, AE = 63, and EO = 16
Find AB and BO
If FO = 25, AO = 65, and BC = 120
Find CF and CO

4. Find the circumcenter of the triangle with vertices R (-6, 0), S (0, 4), O (0, 0)
Graph the triangle.
Find the equation for 2 perpendicular bisectors.
Graph the 2 perpendicular bisectors and find the intersection which is the circumcenter.

5. Homework pages 772-775 #’s 5-12, 15 (all)