Geometry in Action: Crafting the Circumscribed Circle of a Triangle

• Straightedge or Ruler: Essential for drawing straight lines and segments.
• Compass: Critical for creating arcs and circles.
• Pencil: To mark points and draw figures.

Examples

Practice Questions:

1. For an obtuse triangle, where does the circumcenter lie?
2. Construct the circumcircle for a triangle with given side lengths using a ruler and compass. How would the process vary for different triangle types?
3. If a triangle’s sides are given, can we determine the circumradius (radius of the circumcircle) without constructing it?

1. For an obtuse triangle, the circumcenter lies outside the triangle.
2. The core steps remain consistent, but the location of the circumcenter varies. For acute triangles, it’s inside; for right triangles, it’s on the hypotenuse; for obtuse triangles, it’s outside.
3. Yes, using the triangle’s side lengths and semi-perimeter, the circumradius \(R\) can be determined by the formula:
   \(R = \frac{abc}{4K}\)
   Where \(a\), \(b\), and \(c\) are the triangle’s sides, and \(K\) is its area.