What is Dimensional Formula of Angle?

Angle is defined as the ratio of length of arc to radius.

Mathematically,

Angle = Length of Arc / Radius

Dimensional formula of Length = M⁰L¹T⁰
Dimensional formula of Radius = M⁰L¹T⁰

Substituting in the above formula we get,
Dimensional formula of Angle = M⁰L⁰T⁰. We can also say Angle is dimensionless quantity.
SI unit of Angle is radian (rad)