A, B and C are three points on a circle. Prove that the perpendicular bisectors of AB, BC and CA are concurrent
Given: A, B, C are 3 points on a circle
Construction Draw a perpendicular dissector of AB and AC and they meet at a point O. Then join OA, OB and OC.
To prove: perpendicular bisector of AB, BC and CA are concurrent.
Proof: In OEA and
OEB
AE = BE [OL is ^ar bisector of AB]
OE = OE [Common side]
AEO =
BEO [each 90°]
OEA
DEB [By SAS congruence Rule]
OA = OC
Similarly, OFA
OFC [by SAS congruence]
OB = OC = OA = t [Say]
So, we draw a perpendicular from O to the BC on the join
In OMB and
OMC
OB = OC [Proved Above]
OM = OM [Common side]
OMB =
OMC [90° each]
OMB
OMC [by RHS congruence rule]
BN = MC [by corresponding parts of the congruent triangle]
Hence, OM is the perpendicular bisector of side BC.
Hence OL, ON, and OM are concurrent.
Hence proved.