You have submitted an expression. Is there an equation?
I’m guessing that pronumerals a, b and c are side lengths.
If 40° and 50° are angles in triangle ABC, then it is a right triangle such that c²=a²+b², where angle C is the right angle. Therefore if we know a, b or c we can find the other sides using trigonometry. We can’t find any side lengths without knowing what one of them is. We can use sin40 or cos40 to find side lengths.
If a, b and c are angles we need a picture and at least one equation to show what’s going on.