Prove that function f(x)= x is decreasing in (0, ). - Vidyadip

Question

Prove that function $f(x)=\cos x$ is decreasing in $(0, \pi)$.

✓

Answer

Proof of decreasing function: $f^{\prime}(x)=-\sin x$.
Since $\sin x>0$ in $(0, \pi), f^{\prime}(x)<0$, hence it is decreasing.

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