Answer:
Step-by-step explanation:
(cos 4a*cos 2a+sin 4a*sin 2a)/sin 4a
=[cos (4a-2a)]/sin 4a
=(cos 2a)/sin 4a
=(cos 2a) /(2 sin 2a cos 2a)
=1/(2 sin 2a)
=1/2 csc 2a
