I am working with line plotting in a form.
I need to find an angle between two lines AB,BC joined at B.
AB and BC lengths are not same.
I know (x,y) values of A,B and C.
How to find angle at B?

and also
I have Trignometric "TanA" value.
How to find angle 'A' ?

in VB code point, can some body help me?