I think the answer is the third one
Answer:
-4,-2,-1
Step-by-step explanation:
The next term is going to be the previous number divided by two
In triangle, ABD,
AD²= AB²+BD²
AB² = AD²-BD²
AB² = 18²-9² = 324-81 = 243
AB = √243
In triangle, ABC,
AC² = AB²+BC²
AC² = (√243)²+(13)²
AC² = 243+169
AC = √412
AC = 20.29