use pythagorean theorem to solve for the value of x and y of a 60-60-60 degrees.
what are your x's and y's ?
if you take an equilateral triangle and draw an altitude you create a nice 30-60-90 triangle
let the original side be 2 units and it is quite easy to see that the other sides must be
1 , √3 and 2 , 1 opposite the 30°, √3 opposite the 60° and the hypotenuse 2 opposite the 90°
Again memorize this diagram and pattern