Answers:
- AB = 3
- BC = 3
- BD = 9
- AC = 6
- CD = 6
- AD = 12
- The probability is 2/3
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Explanation
Since AC and CD combine to form AD, and because AC = CD, we know that C is the midpoint of AD.
This would mean AD = 12 splits in half to get AC = 6 and CD = 6.
Put another way:
AC + CD = AD
6 + 6 = 12
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Since AC = 6 and AB = BC, we can then split things further in half to get AB = 3 and BC = 3 as well. Use the same idea as the previous section. Point B is the midpoint of AC.
From there we have the following steps
BD = BC + CD
BD = 3 + 6
BD = 9
For more information, search out "midpoint" and also "segment addition postulate".
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The last part of the question asks if we selected a segment at random, what is the probability it is larger than 3 units.
Here are all the segment lengths
- AB = 3
- BC = 3
- BD = 9
- AC = 6
- CD = 6
- AD = 12
There are 6 segments listed above. Of those 6, there are 4 of them that are greater than 3 units long (BD, AC, CD and AD)
The probability we're after is therefore 4/6 = 2/3
As extra info, 2/3 = 0.667 = 66.7% approximately