Question

tan A=2.0503

Answer 1

This reads "The tangent of some angle A is 2.0503 find A."
So to "undo" the tangent function you need its inverse, or the cotangent function.
The Cot(Tan(A))=A. But you need to take the Cotangent of both sides.
This gives A= Cot(2.0503) <-- run that through your calculator.