Question 1190356
the coordinate vertex A is equal to (0,a*sqrt(3)).
see my worksheet below, and my example below that.


<img src = "http://theo.x10hosting.com/2022/020301.jpg" >


<img src = "http://theo.x10hosting.com/2022/020302.jpg" >


the length of each side of your equilateral triangle is 2a.


the length of the altitude of the triangle is x = a * sqrt(3).


that makes point A equal to coordinate point (0, a * sqrt(3)).


let me know if you have any questions.


theo