Step-by-step explanation:
You want to prove a point P on the perpendicular bisector of segment YZ is equidistant from Y and Z.
Statement . . . . Reason
1. PX is the perpendicular bisector of YZ . . . . given
2. angles at X are right angles . . . . definition of perpendicular
3. YX = XZ . . . . definition of bisector
4. PX = PX . . . . reflexive property of congruence
5. ∆PXY ≅ ∆PXZ . . . . LL congruence theorem
6. YP ≅ ZP . . . . CPCTC