amp;mPA=−22=−1amp;∴mBC=1

amp;BC:y=x+5amp;mBP=−32=3−2amp;∴mAC=23amp;AC:y=23x−211⇒2y=3x−11amp;∴C:(21,26)
Let the circumcentre be (h,k)
amp;(h−1)2+(k−1)2=(h+2)2+(k−3)2... (i)amp;(h−1)2+(k−1)2=(h−3)2+(k+1)2... (ii)
Solving (i) and (ii)
amp;h=2−19,k=2−23amp;α+β+2(h+k)amp;=21+26−19−23amp;=2+3=5