Evaluate
Evaluate Cell

Cut
Copy
Copy as
Plain Text
Input Text
Image
Paste

Convert to
InputForm
StandardForm
TraditionalForm
Image

Clear Formatting
Formatting...

Divide Cell
Merge Cells

Publish/Share Cell
Embed...
Email Cell to
Me
Others...
Email Cell...
Deploy Cell as
Instant API
Instant Web Computation
Instant Web Form
Embeddable Code
Advanced
Show Cell Expression...
Cell Update History...
WOLFRAM|DEMONSTRATIONS PROJECT

The Eutrigon Theorem

​
a
b
60°
a
b
c
Δ=Δ+Δ-Δ

The black central triangle with one angle equal to 60° is called a eutrigon. The areas of equilateral triangles constructed on the three faces
a
,
b
, and
c
obey the eutrigon theorem, which gives the area of the black triangle in terms of the areas of the other three triangles.