question in my sin law function



Dear all
        I have a question in my function.Would you help me again?
we know in sin law a/sin(A)=b/sin(B)
if A,b,B is given , then we can solve a
that is my code. I input A,b,B, I want it can solve a by sinLaw function directly. 

(if I don't let a:b/sin(B)*sin(A), can I show a=?)

sinLaw(a,A,b,B):=(
a/sin(A*%pi/180)=b/sin(B*pi/180),
solve(%,[a])
);
[a,A,b,B]:[x,30,sqrt(30),60];
sinLaw(a,A,b,B);


(%o1) sinLaw(a,A,b,B):=(a/sin((A*%pi)/180)=b/sin((B*pi)/180),solve(%,[a]))
(%o2) [x,30,sqrt(30),60]
(%o3) []


 		 	   		  
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