If B is 90 degrees, Tan A is BC / AB. But I don't know what you mean by Tan A by 2.
I am not sure what "tan A 90 degree" means. tan(90 degrees) is an expression that is not defined and so cannot be solved. One way to see why that may be so is to think of tan(x) = sin(x)/cos(x). When x = 90 degrees, sin(90) = 1 and cos(90)= 0 that tan(90) = 1/0 and since division by 0 is not defined, tan(90) is not defined.
To solve for tan x degree 90 you do a few things. First, if x equals 90, then this equals 1.5597 radian or 89.36 degrees. This is the easiest way to solve tan x degree 90.
It is not defined.
The value of tan A is not clear from the question.However, sin A = sqrt[tan^2 A /(tan^2 A + 1)]
tan(135) = -tan(180-135) = -tan(45) = -1
tan(22.5)=0.414213562
The principal range of arc tan is an angle in the open interval (-pi/2, pi/2) radians = (-90, 90) degrees.
On the unit circle at 90 degrees the 90 degrees in radians is pi/2 and the coordinates for this are: (0,1). The tan function = sin/cos. In the coordinate system x is cos and y is sin. Therefore (0,1) ; cos=0, & sin=1 . Tan=sin/cos so tan of 90 degrees = 1/0. The answer of tan(90) = undefined. There can not be a 0 in the denominator, because you can't devide by something with no quantity. Something with no quantity is 0. Or, on a limits point of view, it would be infinity.
90 degrees is one
tan0.15
Tan 42 degrees = 0.9004