1, domain
cosx≠0
x≠kπ+π/2
2. Scope
|cosx|≤ 1
f(x)∈(-∞,0]
3. Monotone interval
X ∈ (2kπ]-π/2,2kπ] increasing function
X∈(2kπ, 2kπ+π/2) Subtraction Function
4. Parity
F (-x) = log2 | cos (-x) | = log2 | cosx | = f (x) even function
5. Minimum positive period
T=π