what is an easy way to describe a golden triangle?

this page gives you a good start

http://mathworld.wolfram.com/GoldenTriangle.html

I also suggest you look into the Fibonacci numbers and the Golden Ratio
(1 + √5)/2

This will spark an interest in a very unique area of mathematics that will keep you occupied for a lifetime, like it has me.
My students used to try to get me off to that topic.

A golden triangle is a geometric shape formed by connecting three points to create a triangle, where the ratio of the lengths of the two sides is equal to the ratio of the longer side to the sum of all three sides. To describe a golden triangle easily, follow these steps:

1. Draw a line segment of any length.
2. From one endpoint, draw a perpendicular line segment of half the length of the first line segment.
3. From the other endpoint, draw a line segment connecting both endpoints of the previous step.
4. The resulting shape is a golden triangle.

By following these steps, you can easily construct a golden triangle and explain its formation.