In acute angled triangle ABC,r=r2+r3−r1 and ∠B>π3 then exhaustive range of a−cb is
None of these
r=r2+r3−r1⇒Δs=Δs−b+Δs−c−Δs−a⇒1s−1s−b=1s−c−1s−a⇒−bs(s−b)=s−a−s+c(s−c)(s−a)=c−a(s−c)(s−a)⇒(s−a)(s−c)s(s−b)=a−cb⇒tan2B2=a−cbSinceBϵ(π3,π2)⇒B2ϵ(π6,π4)⇒a−cbϵ(13,1)