How to use the computer to type the small circle of mathematical degree?

How to use the computer to type the small circle of mathematical degree?

Are you talking about this? 90 ° with Sogou Pinyin or QQ pinyin can come out

What is the symbol of a circle in a triangle?

How to read a horizontal I in a circle, a symbol in mathematics!
Is it theta? The symbol I want to understand is used in data structure to indicate that the upper and lower bounds of a function are given gradually. I know that big O is used only when there is an asymptotic upper bound, and Ω is used only when there is an asymptotic lower bound.

Theta is the eighth Greek letter in Greek. The capital theta is pentaquark in particle physics. It is represented by Θ +. The lowercase theta is the angle of plane in mathematics. The silent tooth friction sound theta in the international phonetic alphabet belongs to auxiliary

What is the mark of a line in a circle
Answer in one day

Do you mean this picture? Meaning: no vehicles are allowed to enter. This sign is set at the exit of the one-way road or the entrance of the section that is not allowed to enter