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Triangles in a Circle

On this web page you can investigate the properties of a triangle with one vertex at the center of a circle and two vertices on the circle.

Sketch

The triangle in this sketch has one vertex at the center of the circle and two vertices on the circle. Drag points A and B to change the triangle. Drag point C to change the radius of the circle. The button will help you answer question 2.

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Investigate

  1. Are the triangles all isosceles? Explain.
  2. If the vertex at the center of the circle has an angle measure of 60°, what is true of the other two angles in the triangle? What kind of a triangle is this?