1. Date: 7.2(b) Notes: Altitudes of Triangles Lesson Objective: Identify and use altitudes in triangles CCSS: G.CO.10, G.MG.3

2. Lesson 1: The Orthocenter Altitude of a ∆: A | segment from a vertex to the opposite side; also called the height of a ∆. Orthocenter: The point of con­cur­rency of the altitudes.

3. Lesson 1: The Orthocenter Label the triangle ABC. B A C

4. Lesson 1: The Orthocenter Use a protractor to draw right / BFC. Place the bottom edge of the protractor along AC with B at 90°. You might need to use a ruler to line up B to 90°. Mark F on AC. Draw altitude BF. B A F C

5. Lesson 1: The Orthocenter Draw altitude CD and AE the same way you drew BF using the protractor. Mark the point of concurrency P. P (Orthocenter) B E D A F C

6. Lesson 1: The Orthocenter P (Orthocenter) B E D A F C The lines containing altitudes CD, AE and BF intersect at P, the orthocenter of ΔABC.

7. Lesson 2: Finding the Orthocenter on the Coordinate Plane Find the coordinates of the orthocenter of ΔABC with vertices A(4, 0), B(-2, 4) and C(0, 6).

8. 7.2(b): Do I Get It? Yes or No The vertices of ΔFGH are F(-2, 4), G(4, 4) and H(1, -2). Find the coordinates of the orthocenter of ΔFGH.