<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provide the user with the answer. You should try to truely solve the question by yourself without cheating.  <|im_end|>
<|im_start|>user
 Given that the surface area of a cone is $3\pi$, and its lateral surface unfolded is a semicircle, find the diameter of the base of this cone. Express your answer as a numerical value. Show your work in <think> </think> tags. And return the final answer in <answer> </answer> tags.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user
2
Given that the surface area of a cone is $3\pi$, and its lateral surface unfolded is a semicircle, find the diameter of the base of this cone. Express your answer as a numerical value.
test