Answer? =b？ +c？ -2bc*cosA

=b？ +c？ -BC

Then 2cosA= 1

cosA= 1/2

A=60

From sine theorem:

c/b=sinC/sinB= 1/2+√3

sinC = sinB( 1/2+√3)C = 180-(A+B)

sin(A+B)=sinB( 1/2+√3)

sin(60+B)=sinB( 1/2+√3)

√3/2 cosb+ 1/2 sinb = 1/2 sinb+√3 sinb

√3/2cosB=√3sinB

tanB= 1/2