The way to represent the diameter of a circle is: the Greek letter φ (phi, pronounced fa √) plus the letter representing the diameter of a circle. Such as Φ o, Φ a, followed by connection =, such as Φ a = 30 mm. In drawing and engineering terminology, the diameter can be directly expressed by Φ plus a number, such as Φ 30.
The standard writing method in CAD, empty set (shape? ):
In 1, Word and Excel spreadsheets, hold down the Alt key first, then enter 8709 on the keypad, and release the ATL key to see "?" This symbol is gone. Because both word and excel are input in Unicode. Other software, such as text documents, is entered in GBK, so it cannot be entered in this way.
2. In Word and Excel, click "Insert-Symbol-Mathematical Operator" and select an empty set (shape? ), note that the character set requires Unicode.
3. Enter %%c in AutoCAD to get this character. When copying from AutoCAD to word, you need to remove the format (only keep the text when pasting), otherwise it will not be displayed because of the font.
4. To use this character in other software, you can open the special symbol of the input method and find the mathematical symbol. Generally, you can find an empty set or copy it from word, excel, cad and other software.
Capital φ stands for:
1. Physics: (1) The magnetic flux φ = BS in Weber Wb. (2) wave stage. (3) Phase of current and voltage. (4) the sign of potential. (5) power. Φ =1/f (f is the focal length, and the unit is m, then the unit is m- 1), and the glasses power d =100Φ (myopia lens power is negative, hyperopia lens power is positive).
2. Mathematics: (1) symbol of the golden section. The number of gold is represented by the Greek letter φ, according to the ratio of pairwise numbers in Fibonacci series, as shown in the figure. We expand this formula and get an extreme value, φ = 1/φ- 1. The final result is calculated as the exact value of the golden section number, which is the golden section number. (2) The number of compound yokes. (3) The included angle between the straight line and the Z axis in three-dimensional coordinates.
3. Cognitive science: In the theory of information integration, φ is used to indicate the degree of consciousness. The higher the φ of a system, the higher its consciousness, whether it is a child's nervous system, a cat's or even a ladybug's.