samy: How do you know when to use inverse sin or sin?
sin(alpha)=opposite/hypotenuse
when you want to solve this equation to "alpha", then you need the inverse of sin, in this calculator "asin()".
asin( sin( alpha ) ) = asin( opposite/hypotenuse )
alpha = asin( opposite/hypotenuse )
so if "opposite" and a "hypotenuse" of a right triangle is given, you can calculate the angle "alpha".
+3146 
