Which of the following statements is not correct? ;

From the options , it is observed that option D is not correct.

Range of $\sin\theta$ is

$-1 \le \sin\theta \le 1$ for $\theta \in R$

$-1 \le \cos\theta \le 1$ for $\theta \in R$

or, $\sin^{2}\theta \le 1$ and $\cos^{2}\theta \le 1$

But $\sin\theta$ and $\cos\theta$ both are constant , it is clearly observed from the graph.

So, $\sin\theta$ and $\cos\theta$ both cannot be 1 simultaneously.

It is also an identity that,

$\sin^{2}\theta+\cos^{2}\theta=1$