If B is the midpoint of segment AC and C is the midpoint of segment AD, what is AD if CD = 9. I think AD = 18, but not sure.

correct

To find the length of AD, we can use the fact that B is the midpoint of segment AC and C is the midpoint of segment AD.

Since B is the midpoint of AC, we can conclude that AB = BC.

Similarly, since C is the midpoint of AD, we can conclude that AC = CD.

Given that CD = 9, we can substitute it into the equation AC = CD:

AC = 9.

Since AB = BC, we can substitute it into the equation AC = AB + BC:

9 = AB + AB.

Simplifying this equation, we can combine like terms:

9 = 2AB.

To isolate AB, we divide both sides of the equation by 2:

9/2 = AB.

So AB = 4.5.

Now we can find the length of AD by adding AB and BC:

AD = AB + BC = 4.5 + 4.5 = 9.

Therefore, AD = 9.

To find AD given that B is the midpoint of segment AC and C is the midpoint of segment AD, we can use the concept of segment midpoints and ratios.

Since B is the midpoint of segment AC, we know that AB is equal to BC. Similarly, since C is the midpoint of segment AD, we know that CD is equal to DA.

Given that CD = 9, we can conclude that DA = 9 as well.

To find AD, we can add the lengths of CD and DA:

AD = CD + DA
AD = 9 + 9
AD = 18

Hence, your assertion that AD = 18 is correct.