Problem with trigonometry equation solution

38 Views Asked by At

While I was revising my trigonometry skills preparing to matriculation exam, I came cross a task I could not solve entirely. I paste my solution of mentioned task and it's content, it is basically about solving equation. The problem is that my solution lacks one answer namely: $x = k * \frac{\pi}{2}$ . The other answers I've found are valid. Can someone explain me this?

https://i.stack.imgur.com/Vyl99.jpg

https://i.stack.imgur.com/6X8o2.jpg

1

There are 1 best solutions below

2
On BEST ANSWER

You are diving by $\cos(x)\sin(x)$ at some point. The problem is that this can be equal to $0$. In which case you get that $\sin(2x)=0$, i.e. $x=\frac{k\pi}{2}$