1. The problem statement, all variables and given/known data I am utterly confused. When I was reading my textbook , I found something unacceptable. While deriving an expression for a modulated wave, It's been given that "A sinusoidal carrier wave can be represented as c (t) = Ac sin (ωt + Φ) where c (t) is the signal strength of the carrier wave. Let m (t) = Am sinωmt represent the message or the modulating signal. The modulated signal cm (t) can be written as cm= (Ac+Amsin ωmt) sin ωct I wonder how's it possible! Shouldn't it be cm (t) = Acsin ωct + Am sinωmt ? But then I made an adhoc assumption - which was not satisfactory - but I thought it could be justified from a more rigorous application of mathematics. So, I continued reading On the next page, I found something in contrast to my "assumption". In the topic "Production of amplitude modulated wave" - According to my textbook "Here the modulating signal Am sinωmt is added to the carrier signal Acsinωt to produce the signal x (t). This signal x (t) = Am sinωmt + Ac sin ωct is passed through a square law device." Now this equation for x (t) is different from the one which was used (in the textbook) earlier. What even is happening?