If D is the midpoint of AC and C is the midpoint of AB and AD=3cm what is the length of AB

The subject is geometry.

To find the length of AB, we can use the concept of midpoint.

Let's label the points: A, B, C, and D. AD is given as 3cm.

Since D is the midpoint of AC, it means that the distance from A to D is half of the distance from A to C. So, AD = DC.

Similarly, C is the midpoint of AB, so the distance from A to C is half of the distance from A to B. Thus, AC = CB.

Now, let's use this information to find the length of AB.

Since AD = DC and AC = CB, we can write the following equations:

AD = DC
3cm = CB

AC = CB
AC = 6cm (since AD = DC = 3cm)

Now, we can use this information to find the length of AB by adding the lengths of AC and CB:

AB = AC + CB
AB = 6cm + 3cm
AB = 9cm

Therefore, the length of AB is 9cm.