Answer:
f(0) = 1/2
Step-by-step explanation:
At x=0, the inequality tells you ...
1/2 ≤ 1 -f(0) ≤ 1/2
That is, ...
1 - f(0) = 1/2
f(0) = 1/2

Answer: Option d.
Step-by-step explanation:
The trigonometric identity needed is:

Knowing that
:
Substitute it into
:

Simplify the expression:

Solve for
. Apply square root at both sides of the expression:


The answer to the question is c.
Isolating the x^2 is the simplest way. it would only be three steps.