for tan2x=3 i get should get two values 71.56 and 251.56 but i dnt knw how to solve to get this two values. pls help me with this. thanx in advance.

Answer 1

reason it this way
let 2x = Ø
then tanØ = 3
Ø must be in quadrants I or III
and using your calculator
Ø = 79.52° or 180+79.52 = 259.52°

then 2x = 79.52 or 2x = 259.52
x=39.76° or x = 129.76°

check:
tan(2x39.76) = tan 79.52 = 3
same for the other one.

I don't know how "they" got your answers.

Answer 2

Sorry your numbers were correct, had my calculator set to GRAD, how silly of me.

Just change my numbers, the method is correct.