Answer: 15.888
Explanation:
You should use SOH CAH TOA or 30-60-90 rules. Since they are asking for approximate they probably want you to use SOH CAH TOA
They have given you the opposite of the angle and hypotenuse. The hypotenuse is always across from the right angle
You will use SOH
Sin 60 =y/18 mult both sides by 18
18 sin 60 =y
y=15.588