what is a surfex angle
I am not sure about a surfex angle! Do you mean a reflex angle? Because I know what that is; an angle greater than 180 degrees (but less than 360)
yes
I'm sorry, but it seems like there might be a mistake or a misspelling in your question. As of my understanding, there is no such term as "surfex angle" in common usage or any widely recognized field. It is possible that you meant to refer to another term or it could be a specific jargon used in a particular industry or context.
To clarify and provide you with accurate information, could you please provide more details or context about the term "surfex angle"? This will help me assist you better and provide a relevant explanation.