1st, recognize that csc=1/sin and sec=1/cos. So we can simplify the equation to sin(6b+pi/8)=cos(2b-pi/8). Generally trig problems are easier if you convert everything to sines and cosines.
2nd, sin & cos are 90 degrees out of phase or pi/2 so the cos(x-pi/2)=sin(x)
3rd, using (2) we get cos(6b+pi/8-pi/2)=cos(2b-pi/8).
this equation is true if the numbers in parentheses are equal or if one is 2•n•pi larger than the other.