Constructor 1

# How to Inscribe an Equilateral Triangle in any Given Circle

video tutorial part
2
of

## Learning Geometry with a Circle Arc Template

with

### Chris Tisdell

Mathematician & Educator

### Materials you will need:

Constructor 1 Template
Unlined Paper / Scrap Paper
Sharp Pencil/s
Fine-point Pen/s
Eraser

### What you will learn in this tutorial:

Inscribing an equilateral triangle within a circle is a fundamental and interesting geometric construction. This classic problem has intrigued mathematicians and geometry enthusiasts for centuries, serving as both an educational tool and a testament to the beauty of mathematics. One intriguing method of accomplishing this construction is demonstrated by Chris Tisdell, who employs a circle arc template to guide us through the intricate steps required to inscribe an equilateral triangle within the confines of a circle.

The goal of this construction is to create a triangle where all three sides are equal in length and all three angles are precisely 60 degrees. Achieving this within the constraints of a circle is not only a mathematical challenge - it looks amazing, too! It highlights the interconnectedness of geometric shapes and the elegance of mathematical relationships.

Chris Tisdell's method begins with the circle itself, with its centre carefully marked. This circle will represent the circumcircle, a circle that passes through all three vertices of the equilateral triangle we aim to inscribe.

To proceed, the next critical step is to establish six points of intersection that will ultimately define the vertices of the equilateral triangle. Tisdell introduces the concept of a circle arc template. This tool helps maintain the consistency and precision required for the construction. The circle arc template is centred at the circle's centre, mirroring the location of the circumcircle's centre. This alignment is vital for maintaining symmetry throughout the construction.

Starting at one point on the circumference of the circle, an arc is drawn with the circle arc template. Moving along the circumference, the template is used to create six equally spaced points of intersection. These six points are essential since they will guide the formation of the equilateral triangle.

Now, with the six points identified, the next step is to connect them to the original circle. This involves drawing three line segments through the circle's centre.

At this point, you'll notice the emergence of the equilateral triangle taking shape. By connecting the endpoints of the three line segments, you effectively close the triangular structure. This final set of lines ensures that all three sides of the triangle are equal in length.

To confirm that the construction meets the criteria of an equilateral triangle, it is essential to verify the angles.Using a protractor, you can measure the angles at each vertex to ensure they are indeed 60 degrees each, a hallmark of an equilateral triangle.

In conclusion, inscribing an equilateral triangle within a circle is a captivating geometric endeavour that demonstrates the intrinsic beauty and symmetry found within mathematical concepts. Chris Tisdell's method, employing a circle arc template, simplifies this classic construction, allowing enthusiasts to appreciate the elegance of geometry and the precise relationships between circles and polygons. It's a testament to the enduring appeal of geometry as both a science and an art form.

### Chris Tisdell

Mathematician & Educator
Chris, a mathematician and educator, is an academic advisor to Mathomat. Chris approached us in 2021 with an interest in the circle templates in Mathomat...
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