Question

Tarefa sobre seno e cosseno de x + y e de x - y

Answer 1

$1+sen(\pi-x).cos(\frac{\pi}{2}+x)= \\ 1+(sen\pi.cosx-senx.cos \pi)(cos(\frac{\pi}{2}).cosx-sen (\frac{\pi}{2}).senx) = \\ 1+(senx)(-senx)= \\ \boxed{1-sen^2x}$