(sin(8a)+2sin(4a))/(1-cos(a)^2 4a)

Question

(sin(8a)+2sin(4a))/(1-cos(a)^2 4a)

Answer 1

(2sin4acos4a+2sin4a)/sin²4a=2sin4a(cos4a+1)/sin²4a=
=2*2cos²2a/sin4a=4cos²2a/2sin2acos2a=2cos2a/sin2a=2ctg2a