Question

Perpendicular Bisectors I'm confused on what to do here

Answer 1

bi(two)...sector(section).  Bisector cuts the segment into two equal sections.  

BC = CD             definition of perpendicular bisector

BC + CD = BD    segment addition postulate

CD + CD = BD   substitution

2CD = BD          added like terms

2CD = 16           substitution

  CD = 8            division property of equality

CD = y + 3         given per graph

y  + 3 = 8           transitive property

  y = 5               subtraction property

Answer: 5