1. 7.2(b) Notes: Altitudes of Triangles
Date:
7.2(b) Notes: Altitudes of Triangles
Lesson Objective: Identify and use altitudes in triangles
CCSS: G.CO.10, G.MG.3
You will need: colored pens, CPR
This is Jeopardy!!!:  This is another name for the height of a triangle.

2. Lesson 1: The Altitudes and 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 Altitudes and Orthocenter
Draw scalene ∆ABC with a straightedge. B
A C

4. Lesson 1: The Altitudes and Orthocenter
With your compass, construct the altitude BG _|_ to AC. B
A C

5. Lesson 1: The Altitudes and Orthocenter
Use a protractor or ID card to draw the altitude CD and AF _|_ to AB and BC. B
A C

6. Lesson 1: The Altitudes and OrthocenterB
A C
The lines containing altitudes CD, AF and BG intersect at P, the orthocenter of ΔABC.

7. Lesson 2: Finding the Altitudes on the Coordinate Plane
Find the altitudes of ΔABC with vertices A(0, -8),
B(2, -2) and C(8, -8).

8. Lesson 3: Finding the Altitudes on the Coordinate Plane
Find the altitudes of ΔXYZ with vertices X(-6, 2),
Y(-3, -2) and Z(-6, -8).

9. 7.2(b): Do I Get It? Yes or No
Use a compass to construct an Isosceles triangle with its base longer than the other 2 sides. Construct the altitude of
each side.
Find the altitudes of each side
of the triangles with the
following vertices.
J(3, -2), K(5, 6) and L(9, -2)
R(-7, 10), S(-1, 10) and
T(-1, 1).
Use a compass to construct an equilateral triangle. Construct the altitude of each side.