If 
and 
show that cos 2A = sin 4B
To prove: cos 2A = sin 4B
We know,
Take LHS:
cos 2A
Now,
Take RHS:
sin 4B
Clearly, LHS = RHS 
Hence Proved
32
If and show that cos 2A = sin 4B
To prove: cos 2A = sin 4B
We know,
Take LHS:
cos 2A
Now,
Take RHS:
sin 4B
Clearly, LHS = RHS
Hence Proved