The capital Greek letter (capital tau) is visually very similar to the uppercase Latin letter T. For that reason, refer to the usage of Capital T for how the symbol appears in math.
Symbol  Format  Data 

Τ  Unicode 

TeX 


SVG 
The Greek letter τ (tau) is used in trigonometry as a constant to represent a full rotation around a circle in radians. The value of τ is approximately 6.28 and can be calculated by dividing any circle's circumference by its radius.