[tex]AB= \sqrt{(X _{A}-X _{B} ) ^{2} +(Y _{A} -Y _{B}) ^{2} } = \sqrt{(1+2) ^{2} +(3-5) ^{2} } = \sqrt{9+4} [/tex]
=>AB=√13
[tex]AC= \sqrt{(X _{A}-X _{C} ) ^{2}+(Y _{A} -Y _{C}) ^{2} } = \sqrt{(1-3) ^{2}+(3+1) ^{2} } = \sqrt{4+16} [/tex]
=>AC=2√5
[tex]BC= \sqrt{(X _{B-X _{C} }) ^{2} +(Y _{B}-Y _{C}) ^{2} }= \sqrt{(-2-3) ^{2}+(5+1)^{2} } [/tex]
=>BC=√61
=>P=√13+2√5+√61√
