In the given right triangle ABC
we have that
[tex]cos(A)=\frac{AC}{AB}\text{ ----> by CAH}[/tex]
substitute given values
[tex]\begin{gathered} cos40^o=\frac{b}{280} \\ solve\text{ for b} \\ b=280*cos40^o \\ b=214.49\text{ in} \end{gathered}[/tex]
therefore
The answer is b=214 inches
