Answer:
√7 ≈ 2.646
Explanation:
The law of cosines is applicable. It tells you ...
c² = a² + b² - 2ab·cos(C) . . . . . where a, b, c are triangle side lengths, and angle C is opposite side c.
Filling in the given information, you have ...
c² = 2² + 3² - 2·2·3·cos(60°) = 4 + 9 - 12·(1/2) = 7
c = √7 ≈ 2.646
The length of the third side is √7, about 2.646 units.