The second one i believe
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Slope intercept is almost the best for everything.
point slope is for when you only know the points on a line
standard form is for when solving systems of equations
The mean absolute deviation is 30
Answer:
Option 1: CD is a perpendicular bisector of AB
Step-by-step explanation:
Let us find out the slopes of various line segments and the Distances and then we will draw the conclusions accordingly.
Formula to find slope

Formula to Find Distance between two points

mAB ( represents , Slope of AB )
1. 
2. 
3. 
4. 
5. 
mAC = mBC , and C is common point , hence these three are collinear points making a straight line whole slope is 



Hence CD ⊥ AB
Also
From Point 4 and point 5 above , we see that
AC = CB
Hence CD bisect AB at C, also CD ⊥ AB
There fore
CD is a perpendicular bisector of AB
Therefor option 1 is true