And T be the mid-point of PR. Since OT is perpendicular bisector of PR. So, equation of OT is given as 2x−y+2=0 Let S be the mid-point of PQ. Now, S will be (
−2+4
2
,
4−2
2
)=(1,1) and OS will be perpendicular bisector of PQ. Equation of OS⇒
y−1
x−1
=
−1
mPQ
∵mPQ=
−2−4
4+2
=−1 ∴ Equation of OS=y−1=1(x−1) ⇒y=x Now, coordinates of O will be the intersection of lines OS and OT. {