Answer:
C but see the discussion below.
Explanation:
Remark
You are given 2 items and ask for a third. That is a classic trig question.
Givens
angle = 27
opposite side = 18
hypotenuse = ?
Solution
Sin(27) = opposite side / hypotenuse
Sin(27) = 18 / hypotenuse Multiply by the hypotenuse
hypotenuse * sin(27) = 18 Divide by sin(27)
hypotenuse = 18 / sin(27)
hypotenuse = 18 / 0.45699
hypotenuse = 39.6484
Comment
This is a very difficult question to pick an answer for. Everything depends on what you have been told about 5 when rounding. I always use a very simple method. It the rounded number is a 5 then you bounce the answer up. Otherwise leave it alone.
I think the correct answer (according to my rule) is that the answer is C, but your teacher could actually use a rule which would round it up to 39.7. I'm going to answer C but if you get it wrong, then D is the answer.