Respuesta :

Short answer C

Comment
How to explain this is not simple. There are all kinds of ways of dealing with it.

One fact is that Sin(A) = Cos (90 - A). But you may not have had that yet.

An easier way is just to use side notation.

The sin of an acute angle in a right triangle is the Opposite over the hypotenuse. 
In this case, Sin(A) = o/h =  BC / AB which you were told was 24/25

Now look at the Cosine of B
It's definition is Adjacent / hypotenuse 
Cos(B) = a/h = 24/25 

Answer
Sin(A) = Cos(B) or
C <<<< answer