find the missing side measure

Answer:
D) 25.5
Step-by-step explanation:
Use basic trigonometry. In this case, use sine.
sin(45) = 18 / x
18 / sin(45) = x
x = 25.4558441227
After you solve this, you will see that 25.5 is close to that.
Hence, the answer to this question is D.