Equilateral Triangle Calculator
Calculate all properties of an equilateral triangle from one side.
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Request a ToolHow to Use the Equilateral Triangle Calculator
This calculator computes all key properties of an equilateral triangle from a single side length.
- Enter the side length. Type a positive number.
- View the results. Area, height, perimeter, inradius, and circumradius are all calculated instantly.
- Copy or share. Use the buttons to save or share your result.
About the Equilateral Triangle
An equilateral triangle has three equal sides and three 60-degree angles. Its area is (sqrt(3)/4) * s^2, and its height is (sqrt(3)/2) * s. The inradius (radius of the inscribed circle) is s / (2 * sqrt(3)), and the circumradius (radius of the circumscribed circle) is s / sqrt(3). Equilateral triangles are the simplest regular polygon and appear in tiling patterns, structural engineering, and design.
Frequently Asked Questions
What is the area formula for an equilateral triangle?
Area = (sqrt(3)/4) * side^2. This comes from the standard triangle area formula using the height (sqrt(3)/2) * side.
What are all the angles in an equilateral triangle?
All three angles are exactly 60 degrees. This is a defining property of equilateral triangles.
What is the relationship between inradius and circumradius?
For an equilateral triangle, the circumradius is exactly twice the inradius.