Question

Arătați ca:
1-sin x =2sin^2 (pi/4-x/2)

Answer 1

aplici cos 2y=1-2sin^2(y)
ecuatia noastra devine
sinx=1-2sin^2 (pi/4-x/2)
sinx=cos[2*(pi/4-x/2)]
sin x=cos(pi/2-x)
sinx=-sinx
2six=0
sinx=0
x=k*pi/2 cu k apartine lui Z