f(x) = cos x is strictly decreasing in `(0, pi)`

f(x) = cos x is strictly increasing in (pi,2pi)

Prove that f(x)="cos"x is strictly decreasing (0,pi)

f(x) = sin x is a strictly increasing in (0, pi/2)

Prove that the function f given by f (x) = log (cos x) is strictly decreasing on (0,pi/2)

Prove that the function f(X) = cosx is strictly decreasing (0,pi) and strictly increasing on (pi,2pi)

Prove that the function f given by f(x) = log sin x is strictly increasing on (0,pi/(2)) and strictly decreasing on (pi/(2),pi) .

f(x) = sin x is a strictly decreasing in (pi/2,pi)

Prove that the function 'f' given by f (x) = log sin x is strictly increasing on (0,pi/2)

Without using the dervative, show that f(x) = |x| is strictly decreasing in (-infty,0)