A=(-5,3)
B=(-1,5)
C=(4,-1)
|AB|=[tex]\sqrt{(x_{B} -x_{A})^{2}+(y_B-y_A)^2\\}[/tex]
|BC|=[tex]\sqrt{(x_C-x_B)^2+(y_C-y_B)^2[/tex]
|CA|=[tex]\sqrt{(x_A-x_C)^2+(y_A-y_C)^2[/tex]
|AB|= [tex]\sqrt{(-1-(-5))^{2} +(5-3)^{2}[/tex] = [tex]\sqrt{4^2+2^2} = \sqrt{ 16+4} = \sqrt{20}[/tex] = [tex]2\sqrt{5[/tex]
|BC|=[tex]\sqrt{(4-(-1))^2+((-1)-5)^2[/tex] = [tex]\sqrt{5^2+(-6)^2} =\sqrt{ 25+36} = \sqrt{61\\[/tex]
|CA|=[tex]\sqrt{(-5-4)^2+(3-(-1))^2[/tex]= [tex]\sqrt{(-9)^2+4^2}=\sqrt{81+16}=\sqrt{97}[/tex]
