Answer:
A
Step-by-step explanation:
We know that identity:
cos^2x+sin^2x=1.
From that we have:
cos^2x=1-sin^2x.
So it is:
cos^2x-sin^x=(1-sin^2x)-sin^2x=1-2sin^2x.
And this is A).
B) is not treu because cos^2 is not sin^2x+1
C) is not true because cos^2x-sin^x=1 is false.
D) is not treu because cos^2x is not sin^2x-1
