Express g(x)=sin 2x-1 as a cosine function.
The cosine function is related to the sine function through the identity:
cos(x) = sin(x + π/2)
Using this identity, we can express g(x) = sin(2x) - 1 as a cosine function:
g(x) = sin(2x) - 1
= cos(2x + π/2) - 1
Therefore, g(x) = cos(2x + π/2) - 1 is the expression of g(x) as a cosine function.