Answer:
sin F = a/c
Explanation:
The sin ratio by definition for a given angle is the side opposite that angle over the hypotenuse. The only thing that will never change sides in a right triangle is the hypotenuse. In other words, no matter what angle you look at, while the side opposite one angle may be the adjacent side to a different angle, the hypotenuse is always the hypotenuse. That means that c is the hypotenuse in our triangle. The side opposite angle F is a, so the sin of F = a/c.