मेगास्थनीज कौन था / history / gk / gs / #upsc / #ssc / #ias / #ips / #pcs / #ssccgl / #shorts

Let I be the incentre of triangleABC . Using vectors prove that for any point P a(PA)^2+b(PB)^2+c(PC)^2=a(IA)^2+b(IB)^2+c(IC)^2+(a+b+c) (IP)^2 where a, b, c have usual meanings.