Step-by-step explanation:
You mean the answer is - 14
So - 14 + (-4) =
- 14 - 4 = 18
II(RS is a median) and III(RS is a side of RST)
I think you meant to have more of a problem stated.
Basically, you use the Law of Sines when you have 2 angles but the length of only one side.
The formula for this law is
a / sine(A) = b / sine(B) = c / sine(C)