Answer: Option B.
Step-by-step explanation:
Here we can start with the relation
cos(x)^2 + sin(x)^2 = 1
multiply both sides by cos(x)
cos(x) = cos(x)^3 + sin(x)^2*cos(x) = cos(x)^2*(cos(xI + sin(x)^2/cos(x))
now we can replace sin(x)/cos(x) = tg(x)
cos(x) = cos(x)^2*(cos(x) + sin(x)*tan(x))
So the correct option is B
