in a right triangle there is a forumula that a squared + b squared = c squared where a and b are legs of the triangle and c is the hypotenuse. so if you take what you know x is one leg, 2x is the hypotenuse and 4 root 3 is the other leg and plug into the equation you get
x^2 + (4 root 3)^2 = (2x)^2 simplify x^2 + 48 = 4x^2 subtract x^2 from both sides and you get
48= 3x^2 divide by 3 and you get 16=x^2 4=x for your unknown leg and 8=2x for your hypotenuse.
