Answer: Missing parts are,
In first blank,
,
In second blank, SAS postulate
In third blank, CPCTC postulate
Step-by-step explanation:
Since, Here D is the mid point on the line segment AC.
And BD is a perpendicular to the line AC.
Therefore, In triangles ADB and CDB ( shown in figure)
AD\cong DC ( By the definition of mid point)
( right angles )
( reflexive)
Thus, By SAS ( side angle side )postulate,
![\triangle ADB\cong \triangle CDB](https://tex.z-dn.net/?f=%5Ctriangle%20ADB%5Ccong%20%5Ctriangle%20CDB)
So, by CPCTC( Corresponding parts of congruent triangles are congruent)
![AB\cong CB](https://tex.z-dn.net/?f=AB%5Ccong%20CB)
Now, By definition of congruent segment,
AB=CB
By definition of equidistant,
B is equally far from both A and C.