How do you show that a triangle with vertices (13,-2), (9,-8), (5,-2) is isosceles?

1 Answer
Jan 6, 2016

Find the length of the triangle's segments and prove that two are equal but the third is different. In case, P1P1=P2P3=sqrt(50) and P1P3=8 => triangle_(P1P2P3) is isosceles

Explanation:

Length of the triangle's segments:
P1P2=sqrt((9-13)^2+(-8+2)^2)=sqrt (16+36)=sqrt(50)
P1P3=sqrt((5-13^2+(-2+2)^2)=sqrt(64+0)=8
P2P3=sqrt((5-9)^2+(-2+8)^2)=sqrt(16+36)=sqrt(50

As we can see two sides of the triangle are equal (P1P2=P2P3=sqrt(50)) but the third one is different (P1P3=8): so triangle_(P1P2P3) is isosceles.