4. One side of a triangle is 2, the median of this side is 1, and the sum of the other two sides is $1+\sqrt{3}$, then the area of this triangle is:
(A) 1;
(B) $\frac{1}{2} \sqrt{3}$;
(C) $\sqrt{3}$;
(D)

Cannot be determined.
Answer: (B).
From the given side of the triangle being 2, and the median to this side being 1, we can determine that this triangle is a right triangle, with the hypotenuse being 2. Since the sum of the two legs is $1+\sqrt{3}$, we can find that one leg is 1 and the other is $\sqrt{3}$. Therefore, the area of this triangle is $\frac{1}{2} \sqrt{3}$.