Try it yourself:
| @1 |
pi
|
|
| @2 |
sin(pi/2)
|
pi is the ratio of a circle’s circumference to its diameter, approximately 3.14159. It is exact and dimensionless.
Circle area is pi times radius squared. Use pi with sin(), cos(), and tan(); use phi for a separate algebraic constant.
Trigonometric functions normally use radians. Preserve pi symbolically until numeric output.
Enter pi on a calculator line to see its built-in value, or place the name inside a longer expression. Keep any displayed unit attached when converting or combining physical quantities, and check that every other value uses a compatible dimension.
The example above is editable, so you can replace surrounding values and test the constant in your own formula. Browse all constants to compare related values and notation.