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?

$e^x$ is strictly increasing on R...$\cos\theta $ is decreasing in first quadrant...so the answer must be $\sin\theta$..
