Question

Triangle ABC has the following vertices:
A(7,-2)
B(-1,-8)
C(5,0)
Is triangle ABC an isosceles triangle, and why?

Answer 1

Calculate the lengths of the 3 sides of the triangle:

AB =

$\sqrt{(7 - ( - 1)) ^{2} + (( - 2) - ( - 8))^{2} } = 10$

BC =

$\sqrt{(( - 1) - 5) ^{2} + (( - 8) - 0)^{2} } = 10$

AC =

$\sqrt{(7 - 5) ^{2} + (( - 2) - 0)^{2} } = 2 \sqrt{2}$

Because AB = BC

=> ️ABC is an isoscelea triangle at B