Theorem of Pythagoras: a²+b²=c², where a, b is legs and c is hypotenuse.
We've got one leg known, let it be a=sqrt 3,
and the hypotenuse - c=2sqrt3
Putting these into the theorem, we get an equation: (sqrt3)²+b²=(2sqrt3)² . Solving it, we get:
3+b²=4*3
3+b²=12
b²=9
This equation has two possible roots: b=3 and b=-3. Since this is a triangle, there can't be a side with a negative value => b=3.
The answer is a. 3
