How do you use SOH CAH TOA?

If you have a right angled triangle, it is made up of a hypotenuse, adjacent and opposite. In SOH CAH TOA, the middle letter goes up, so when we use the equation, it will be sin=opposite/hypotenuse, etc. If, for example I've been asked to find the angle x and been told the opposite is length of 5 and the hypotenuse a length of 10, I can think about what I have been given. So I have the SOH. Therefore I need to do 5 (opposite) / 10 (hypotenuse). We now know sinx=0.5, so to find x we need to use sin-1(0.5)=30