How to construct an altitude to a triangle

You are given a triangle. The task is to draw an altitude through C.

First draw a circle using A as a center point and the line segment AC as the radius.

Then draw a second circle using B as center point and the line segment BC as the radius.

1. Time to practice! Draw an altitude to each triangle from the top vertex. Notice the second triangle is
    obtuse, so the altitude will be outside of the triangle.
 

2. Draw all three altitudes to this triangle. Can you notice something special about
    the three altitudes you draw?

This lesson is taken from Maria Miller's book Math Mammoth Geometry 3, and posted at www.HomeschoolMath.net with permission from the author. Copyright © Maria Miller.