That's because of the identityHi friends,
I have a book with some study examples and I stumbled upon this sum, tried it myself, but then realized I have no clue as to where they get the part marked with a circle?View attachment 35585
Ahhh...Thank you kindly jonah2.0...do appreciate..!!Beer assisted recall follows.
That's because of the identity
[imath]sin(2x)=2sin(x)cos(x)[/imath] or [imath]\frac{1}{2}sin(2x)=sin(x)cos(x)[/imath]