I can't solve this easy question ?
You can't cancel out like that.
Remember that $\displaystyle \csc(x) = \frac{1}{\sin(x)} $
Therefore, try this:
$\displaystyle \frac{\sin(x) + \cos^2(x)}{\sin(x)} = \csc(x) $
$\displaystyle \sin(x) + \cos^2(x) = \frac{1}{\sin(x)} \times \sin(x) $
$\displaystyle \sin(x) + \cos^2(x) = 1 $
Now, remember that $\displaystyle sin^2(x) + cos^2(x) = 1 $. You can use this to write $\displaystyle \cos^2(x) $ in terms of $\displaystyle \sin(x) $ which will give you a quadratic in $\displaystyle \sin(x) $ to solve.