What do I do wrong? Trigonometry

[Silvestr]

tg A = tg B / cos C

A= 145° 49'49''
C = 23°26.44'

Need to find B

tg A = tg B / 0.917538086825

-0.679141161015 = tg B / 0.917538086825

tg B = -0.679141161015 *0.917538086825 = −0,62313788156

What is next?

 

[ksdhart2]

What do you know about inverse trig functions? Specifically: \(\tan^{-1}(\tan(B)) = \text{???}\). Then whatever you do to one side of the equation you have to also do to the other, so...