guest: sin(x)=7/13 ???
This is an inverse sine or arcsine problem because it is the angle that you need to find.
If you are using degrees, check that you calulator is in degrees mode. There will probably be a tiny little D at the top of the screen.
now
inverse sign of (7/13) is written as, sin
-1(7/13)
(Don't confuse this with a power of -1 they are completely different, the notation is dumb, but what can you do )
Now, if you look at the sin button on your calculator it will have a little sin
-1 written above (in colour coding) . This means that you have to press an INV or a 2nd funct button at the top of the calc to use the notation
so it's
INV SIN (7/13) = (then you might need to press the degrees minutes and seconds button to get it to display as an angle)
I hope that you got a lot out of this explanation!
+118654 
