|AB| signifies "distance between A and B," |BC| "distance between B and C, and |CA| "distance between C and A." Using the distance formula
Find the numerical value of these three distances / lengths.
Sounds as though there was a diagram here which has not come through and is thus not visible.
|AB|^2 = (11-8)^2 + (13-2)^2 = 9 + 121 = 130.
Likewise, find |BC|^2 and |CA|^2.
Does the sum of the smaller two squares equal the largest square? If so, the triangle is a right triangle.
Are any two of these squares equal? If so, this is an isosceles triangle.