Lesson
A triangle is said to be inscribed in a circle if all of the vertices of the triangle lie on the circumference of the circle. By this definition, the sides of the triangle are also chords of the circle, and the angles are inscribed angles.
Using only a protractor, straight edge, pencil, and piece of paper, construct the following equilateral triangle. Then answer the questions at the bottom of the page. Use the videos and the lesson on basic constructions to help you.
Equilateral Triangle inscribed in a circle
Summary Question
1. How can you be certain that the sides of the triangle are all the same length?