Answer:
-3
Explanation:
In the attached image we can see the tan(x/2) relation with sine and cosine
tan(x/2)=sinx/(1+cosx)
sinx=-3/5
and from the triangle we can see that the cosine is equal to -4/5 (this triangle is also called a notable triangle of sides 3,4,5 in lenght)
tan(x/2)=(-3/5)/(1-4/5)
tan(x/2)=-3