Is $\cos\theta$ or $\sin\theta$ an increasing function in first quadrant? The question asks whether $\sin\theta$ is increasing function in first quadrant or $\cos\theta$ is increasing function in first quadrant. Other options are $e$ and $e^x$. I think the answer is $\sin\theta$ because if we put the values of angles from $0^{\circ}$ to $90^{\circ}$ the answer goes from $0$ to $1$. But the answer at the back of the book is $\cos\theta$. Am I taking this in wrong way? Or the answer is wrong? I just want to confirm it. Should I derivate it?

This should be a comment, but I wanted to make sure that everybody saw it:
In the first quadrant, the “co” functions all are decreasing, and the “non-co” functions all are increasing.
