Answer:
B.) 7 in
Explanation:
A regular hexagon can be divided into 6 congruent equilateral triangle. The measure of an angle of an equilateral triangle is 60 deg. The angle formed by sides b and c measures 60 deg.
tan A = opp/adj
tan 60 deg = 12/b
b * tan 60 deg = 12
b = 12/(tan 60 deg)
b = 7 in